Pallet proc macro doc improvements (#7955)

* Fix weight syntax in comments

* Mention to add `IsType` bound

* Link to subsee

* Fix link

* Update frame/support/procedural/src/pallet/parse/call.rs

Co-authored-by: David <dvdplm@gmail.com>

* Apply review suggestion from @dvdplm

, make StorageInstance doc link

* fix ui test

Co-authored-by: David <dvdplm@gmail.com>
Co-authored-by: thiolliere <gui.thiolliere@gmail.com>

substrate/frame/support/procedural/src/pallet/parse/call.rs

@@ -57,7 +57,7 @@ pub struct CallVariantDef {
 }
 
 /// Attributes for functions in call impl block.
-/// Parse for `#[pallet::weight = expr]`
+/// Parse for `#[pallet::weight(expr)]`
 pub struct FunctionAttr {
 	weight: syn::Expr,
 }
@@ -175,7 +175,7 @@ impl CallDef {
 
 				if call_var_attrs.len() != 1 {
 					let msg = if call_var_attrs.is_empty() {
-						"Invalid pallet::call, require weight attribute i.e. `#[pallet::weight = $expr]`"
+						"Invalid pallet::call, requires weight attribute i.e. `#[pallet::weight($expr)]`"
 					} else {
 						"Invalid pallet::call, too many weight attributes given"
 					};

substrate/frame/support/src/lib.rs

@@ -1388,8 +1388,9 @@ pub mod pallet_prelude {
 /// ### Macro expansion
 ///
 /// For each storage item the macro generates a struct named
-/// `_GeneratedPrefixForStorage$NameOfStorage`, implements `StorageInstance` on it using the 
-/// pallet and storage name. It then uses it as the first generic of the aliased type.
+/// `_GeneratedPrefixForStorage$NameOfStorage`, and implements [`StorageInstance`](traits::StorageInstance)
+/// on it using the pallet and storage name. It then uses it as the first generic of the aliased
+/// type.
 ///
 ///
 /// The macro implements the function `storage_metadata` on `Pallet` implementing the metadata for
@@ -1909,7 +1910,8 @@ pub mod pallet_prelude {
 /// 	```
 /// 5. **migrate Config**: move trait into the module with
 /// 	* all const in decl_module to `#[pallet::constant]`
-/// 6. **migrate decl_module**: write:
+/// 	* add bound `IsType<<Self as frame_system::Config>::Event>` to `type Event`
+/// 7. **migrate decl_module**: write:
 /// 	```ignore
 /// 	#[pallet::hooks]
 /// 	impl<T: Config> Hooks for Pallet<T> {
@@ -1996,8 +1998,9 @@ pub mod pallet_prelude {
 ///
 /// ## Checking upgrade guidelines:
 ///
-/// * compare metadata. This checks for:
-/// 	* call, names, signature, doc
+/// * compare metadata. Use [subsee](https://github.com/ascjones/subsee) to fetch the metadata
+/// and do a diff of the resulting json before and after migration. This checks for:
+/// 	* call, names, signature, docs
 /// 	* event names, docs
 /// 	* error names, docs
 /// 	* storage names, hasher, prefixes, default value

substrate/frame/support/test/tests/pallet_ui/call_missing_weight.stderr

-error: Invalid pallet::call, require weight attribute i.e. `#[pallet::weight = $expr]`
+error: Invalid pallet::call, requires weight attribute i.e. `#[pallet::weight($expr)]`
   --> $DIR/call_missing_weight.rs:17:3
    |
 17 |         fn foo(origin: OriginFor<T>) -> DispatchResultWithPostInfo {}