Clean up the asset-tx-payment Pallet (#657)

* move dev-deps into correct section

* generate Readme.md

* Update pallets/asset-tx-payment/README.md

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>

cumulus/pallets/asset-tx-payment/Cargo.toml

@@ -16,8 +16,6 @@ targets = ["x86_64-unknown-linux-gnu"]
 # Substrate dependencies
 frame-support = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 frame-system = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
-pallet-assets = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
-pallet-authorship = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 pallet-transaction-payment = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 sp-core = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
 sp-io = { git = "https://github.com/paritytech/substrate", branch = "master", default-features = false }
@@ -32,6 +30,9 @@ serde = { version = "1.0.101", optional = true }
 [dev-dependencies]
 smallvec = "1.4.1"
 serde_json = "1.0.41"
+
+pallet-assets = { git = "https://github.com/paritytech/substrate", branch = "master" }
+pallet-authorship = { git = "https://github.com/paritytech/substrate", branch = "master" }
 pallet-balances = { git = "https://github.com/paritytech/substrate", branch = "master" }
 sp-storage = { git = "https://github.com/paritytech/substrate", branch = "master" }
 

cumulus/pallets/asset-tx-payment/README.md

+# pallet-asset-tx-payment
+
+## Asset Transaction Payment Pallet
+
+This pallet allows runtimes that include it to pay for transactions in assets other than the
+native token of the chain.
+
+### Overview
+It does this by extending transactions to include an optional `AssetId` that specifies the asset
+to be used for payment (defaulting to the native token on `None`). It expects an
+[`OnChargeAssetTransaction`] implementation analogously to [`pallet-transaction-payment`]. The
+included [`FungiblesAdapter`] (implementing [`OnChargeAssetTransaction`]) determines the fee
+amount by converting the fee calculated by [`pallet-transaction-payment`] into the desired
+asset.
+
+### Integration
+This pallet wraps FRAME's transaction payment pallet and functions as a replacement. This means
+you should include both pallets in your `construct_runtime` macro, but only include this
+pallet's [`SignedExtension`] ([`ChargeAssetTxPayment`]).
+
+License: Apache-2.0