docs: add docs on proto annotations (#15548)

UPGRADING.md

@@ -356,6 +356,11 @@ In case a module requires to return `abci.ValidatorUpdate` from `EndBlock`, it c
 + EndBlock(context.Context) ([]abci.ValidatorUpdate, error)
 ```
 
+`GetSigners()` is no longer required to be implemented on `Msg` types. The SDK will automatically infer the signers from the `Signer` field on the message. The signer field is required on all messages unless using a custom signer function.
+
+
+To find out more please read the [signer field](./05-protobuf-annotations.md#signer) &  [here](https://github.com/cosmos/cosmos-sdk/blob/7352d0bce8e72121e824297df453eb1059c28da8/docs/docs/build/building-modules/02-messages-and-queries.md#L40)documentation. 
+<!-- Link to docs once redeployed -->
 #### `x/auth`
 
 For ante handler construction via `ante.NewAnteHandler`, the field `ante.HandlerOptions.SignModeHandler` has been updated to `x/tx/signing/HandlerMap` from `x/auth/signing/SignModeHandler`. Callers typically fetch this value from `client.TxConfig.SignModeHandler()` (which is also changed) so this change should be transparent to most users.

docs/docs/build/building-modules/02-messages-and-queries.md

@@ -49,10 +49,10 @@ https://github.com/cosmos/cosmos-sdk/blob/9c1e8b247cd47b5d3decda6e86fbc3bc996ee5
 
 In 0.50+ signers from the `GetSigners()` call is automated via a protobuf annotation. 
 
-<!-- TODO: remove this todo after https://github.com/cosmos/cosmos-sdk/pull/15548 is merged -->
+Read more about the signer field [here](./05-protobuf-annotations.md).
 
 ```protobuf reference 
-https://github.com/cosmos/cosmos-sdk/blob/e6848d99b55a65d014375b295bdd7f9641aac95e/proto/cosmos/bank/v1beta1/tx.proto#L41
+https://github.com/cosmos/cosmos-sdk/blob/e6848d99b55a65d014375b295bdd7f9641aac95e/proto/cosmos/bank/v1beta1/tx.proto#L40
 ```
 
 If there is a need for custom signers then there is an alternative path which can be taken. A function which returns `signing.CustomGetSigner` for a specific message can be defined. 

docs/docs/build/building-modules/05-protobuf-annotations.md

@@ -0,0 +1,121 @@
+---
+sidebar_position: 1
+---
+
+# ProtocolBuffer Annotations
+
+This document explains the various protobuf scalars that have been added to make working with protobuf easier for Cosmos SDK application developers
+
+## Signer
+
+Signer specifies which field should be used to determine the signer of a message for the Cosmos SDK. This field can be used for clients as well to infer which field should be used to determine the signer of a message.
+
+Read more about the signer field [here](./02-messages-and-queries.md).
+
+```protobuf reference 
+https://github.com/cosmos/cosmos-sdk/blob/e6848d99b55a65d014375b295bdd7f9641aac95e/proto/cosmos/bank/v1beta1/tx.proto#L40
+```
+
+```proto
+option (cosmos.msg.v1.signer) = "from_address";
+```
+
+## Scalar
+
+The scalar type defines a way for clients to understand how to construct protobuf messages according to what is expected by the module and sdk.
+
+```proto
+(cosmos_proto.scalar) = "cosmos.AddressString"
+```
+
+Example of account address string scalar:
+
+```proto reference 
+https://github.com/cosmos/cosmos-sdk/blob/e6848d99b55a65d014375b295bdd7f9641aac95e/proto/cosmos/bank/v1beta1/tx.proto#L46
+```
+
+Example of validator address string scalar: 
+
+```proto reference 
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/distribution/v1beta1/query.proto#L87
+```
+
+Example of Decimals scalar: 
+
+```proto reference
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/distribution/v1beta1/distribution.proto#L26
+```
+
+Example of Int scalar: 
+
+```proto reference
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/gov/v1/gov.proto#L137
+```
+
+There are a few options for what can be provided as a scalar: cosmos.AddressString, cosmos.ValidatorAddressString, cosmos.ConsensusAddressString, cosmos.Int, cosmos.Dec. 
+
+## Implements_Interface
+
+Implement interface is used to provide information to client tooling like [telescope](https://github.com/cosmology-tech/telescope) on how to encode and decode protobuf messages. 
+
+```proto
+option (cosmos_proto.implements_interface) = "cosmos.auth.v1beta1.AccountI";
+```
+
+## Amino
+
+The amino codec was removed in 0.50.0, this means there is not a need register `legacyAminoCodec`. To replace the amino codec, Amino protobuf annotations are used to provide information to the amino codec on how to encode and decode protobuf messages. 
+
+:::note
+Amino annotations are only used for backwards compatibility with amino. New modules are not required use amino annotations.
+:::
+
+The below annotations are used to provide information to the amino codec on how to encode and decode protobuf messages in a backwards compatible manner. 
+
+### Name
+
+Name specifies the amino name that would show up for the user in order for them see which message they are signing.
+
+```proto
+option (amino.name) = "cosmos-sdk/BaseAccount";
+```
+
+```proto reference
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/bank/v1beta1/tx.proto#L41
+```
+
+### Field_Name
+
+Field name specifies the amino name that would show up for the user in order for them see which field they are signing.
+
+```proto
+uint64 height = 1 [(amino.field_name) = "public_key"];
+```
+
+```proto reference
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/distribution/v1beta1/distribution.proto#L166
+```
+
+### Dont_OmitEmpty 
+
+Dont omitempty specifies that the field should not be omitted when encoding to amino. 
+
+```proto
+repeated cosmos.base.v1beta1.Coin amount = 3 [(amino.dont_omitempty)   = true];
+```
+
+```proto reference
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/bank/v1beta1/bank.proto#L56
+```
+
+### Encoding 
+
+Encoding specifies the amino encoding that should be used when encoding to amino. 
+
+```proto
+(amino.encoding)         = "legacy_coins",
+```
+
+```proto reference
+https://github.com/cosmos/cosmos-sdk/blob/e8f28bf5db18b8d6b7e0d94b542ce4cf48fed9d6/proto/cosmos/bank/v1beta1/genesis.proto#L23
+```