Update documentation for uniques (This PR renames classes and instances to...

Update documentation for uniques (This PR renames classes and instances to collections and items in the Uniques pallet in order to follow the commonly accepted NFTs terminology.) (#13322)

* Update documentation for uniques

The documentation was outdated after merge of #11389
Using the widely spread term collections and item instead
of the previous class and instance.

* Update README.md

---------

Co-authored-by: Jegor Sidorenko <5252494+jsidorenko@users.noreply.github.com>
Co-authored-by: Jegor Sidorenko <jegor@parity.io>

substrate/frame/uniques/README.md

@@ -4,67 +4,71 @@ A simple, secure module for dealing with non-fungible assets.
 
 ## Overview
 
-The Uniques module provides functionality for asset management of non-fungible asset classes, including:
+The Uniques module provides functionality for non-fungible tokens' management, including:
 
-* Asset Issuance
-* Asset Transfer
-* Asset Destruction
+* Collection Creation
+* Item Minting
+* Item Transfers
+* Item Trading methods
+* Attributes Management
+* Item Burning
 
-To use it in your runtime, you need to implement the assets [`uniques::Config`](https://paritytech.github.io/substrate/master/pallet_uniques/pallet/trait.Config.html).
+To use it in your runtime, you need to implement [`uniques::Config`](https://paritytech.github.io/substrate/master/pallet_uniques/pallet/trait.Config.html).
 
 The supported dispatchable functions are documented in the [`uniques::Call`](https://paritytech.github.io/substrate/master/pallet_uniques/pallet/enum.Call.html) enum.
 
 ### Terminology
 
-* **Asset issuance:** The creation of a new asset instance.
-* **Asset transfer:** The action of transferring an asset instance from one account to another.
-* **Asset burning:** The destruction of an asset instance.
-* **Non-fungible asset:** An asset for which each unit has unique characteristics. There is exactly
-  one instance of such an asset in existence and there is exactly one owning account.
+* **Collection creation:** The creation of a new collection.
+* **Item minting:** The action of creating a new item within a collection.
+* **Item transfer:** The action of sending an item from one account to another.
+* **Item burning:** The destruction of an item.
+* **Non-fungible token (NFT):** An item for which each unit has unique characteristics. There is exactly
+  one instance of such an item in existence and there is exactly one owning account.
 
 ### Goals
 
 The Uniques pallet in Substrate is designed to make the following possible:
 
-* Allow accounts to permissionlessly create asset classes (collections of asset instances).
-* Allow a named (permissioned) account to mint and burn unique assets within a class.
-* Move asset instances between accounts permissionlessly.
-* Allow a named (permissioned) account to freeze and unfreeze unique assets within a
-  class or the entire class.
-* Allow the owner of an asset instance to delegate the ability to transfer the asset to some
+* Allow accounts to permissionlessly create NFT collections.
+* Allow a named (permissioned) account to mint and burn unique items within a collection.
+* Move items between accounts permissionlessly.
+* Allow a named (permissioned) account to freeze and unfreeze unique items within a
+  collection or the entire collection.
+* Allow the owner of an item to delegate the ability to transfer the item to some
   named third-party.
 
 ## Interface
 
 ### Permissionless dispatchables
-* `create`: Create a new asset class by placing a deposit.
-* `transfer`: Transfer an asset instance to a new owner.
-* `redeposit`: Update the deposit amount of an asset instance, potentially freeing funds.
+* `create`: Create a new collection by placing a deposit.
+* `transfer`: Transfer an item to a new owner.
+* `redeposit`: Update the deposit amount of an item, potentially freeing funds.
 * `approve_transfer`: Name a delegate who may authorise a transfer.
 * `cancel_approval`: Revert the effects of a previous `approve_transfer`.
 
 ### Permissioned dispatchables
-* `destroy`: Destroy an asset class.
-* `mint`: Mint a new asset instance within an asset class.
-* `burn`: Burn an asset instance within an asset class.
-* `freeze`: Prevent an individual asset from being transferred.
+* `destroy`: Destroy a collection.
+* `mint`: Mint a new item within a collection.
+* `burn`: Burn an item within a collection.
+* `freeze`: Prevent an individual item from being transferred.
 * `thaw`: Revert the effects of a previous `freeze`.
-* `freeze_class`: Prevent all asset within a class from being transferred.
-* `thaw_class`: Revert the effects of a previous `freeze_class`.
-* `transfer_ownership`: Alter the owner of an asset class, moving all associated deposits.
-* `set_team`: Alter the permissioned accounts of an asset class.
+* `freeze_collection`: Prevent all items within a collection from being transferred.
+* `thaw_collection`: Revert the effects of a previous `freeze_collection`.
+* `transfer_ownership`: Alter the owner of a collection, moving all associated deposits.
+* `set_team`: Alter the permissioned accounts of a collection.
 
 ### Metadata (permissioned) dispatchables
-* `set_attribute`: Set a metadata attribute of an asset instance or class.
-* `clear_attribute`: Remove a metadata attribute of an asset instance or class.
-* `set_metadata`: Set general metadata of an asset instance.
-* `clear_metadata`: Remove general metadata of an asset instance.
-* `set_class_metadata`: Set general metadata of an asset class.
-* `clear_class_metadata`: Remove general metadata of an asset class.
+* `set_attribute`: Set an attribute of an item or collection.
+* `clear_attribute`: Remove an attribute of an item or collection.
+* `set_metadata`: Set general metadata of an item.
+* `clear_metadata`: Remove general metadata of an item.
+* `set_collection_metadata`: Set general metadata of a collection.
+* `clear_collection_metadata`: Remove general metadata of a collection.
 
 ### Force (i.e. governance) dispatchables
-* `force_create`: Create a new asset class.
-* `force_asset_status`: Alter the underlying characteristics of an asset class.
+* `force_create`: Create a new collection.
+* `force_asset_status`: Alter the underlying characteristics of a collection.
 
 Please refer to the [`Call`](https://paritytech.github.io/substrate/master/pallet_uniques/pallet/enum.Call.html) enum
 and its associated variants for documentation on each function.