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 <[email protected]>

* Apply review suggestion from @dvdplm

, make StorageInstance doc link

* fix ui test

Co-authored-by: David <[email protected]>
Co-authored-by: thiolliere <[email protected]>