Update Building Modules documentation (#7473)

* Update module-manager.md

* Update modules #messages doc

* Fix typo

* Update message implementation example link

* Update messages-and-queries.md#queries doc

* Update querier.md

* Update handler.md

* Update links in beginblock-endblock.md

* Update keeper.md

* Update invariants.md

* Update genesis.md

* Update module-interfaces.md#transaction-commands

* Update module-interfaces.md#query-commands

* Update module-interfaces.md#flags

* Update module-interfaces.md#rest

* Update structure.md

* Update module-interfaces.md#grpc

* Update errors.md

* Update module-interfaces.md#grpc-gateway-rest

* Add more info on swagger

* Address comments

* Fix go.sum

* Fix app-anatomy.md

* Update docs/building-modules/module-interfaces.md

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* Update docs/building-modules/querier.md

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* Update docs/building-modules/querier.md

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* Update docs/building-modules/module-interfaces.md

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* Update docs/building-modules/module-interfaces.md

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* Address part of review comments

* Update old ref of RegisterQueryService

* Add example code for Manager

* Update queriers.md to query-services.md and refs

* Add new query-services.md

* Revert "Update old ref of RegisterQueryService"

This reverts commit 1ea1ea8559604d5c0aa13951b3016967438da2a5.

* Update keeper.md

* Update handler.md

* Update handler.md

* Update messages-and-queries.md

* Update docs/basics/app-anatomy.md

Co-authored-by: Amaury Martiny <amaury.martiny@protonmail.com>

* Update docs/building-modules/intro.md

Co-authored-by: Amaury Martiny <amaury.martiny@protonmail.com>

* Fix typo

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>
Co-authored-by: Amaury Martiny <amaury.martiny@protonmail.com>

docs/basics/app-anatomy.md

@@ -182,7 +182,7 @@ Finally, each module should also implement the `RegisterQueryService` method as
 
 Legacy queriers were queriers used before the introduction of Protobuf and gRPC in the SDK. They are present for existing modules, but will be deprecated in a future release of the SDK. If you are developing new modules, gRPC query services should be preferred, and you only need to implement the `LegacyQuerierHandler` interface if you wish to use legacy queriers.
 
-[`Queriers`](../building-modules/querier.md) are very similar to `handlers`, except they serve user queries to the state as opposed to processing transactions. A [query](../building-modules/messages-and-queries.md#queries) is initiated from an [interface](#application-interface) by an end-user who provides a `queryRoute` and some `data`. The query is then routed to the correct application's `querier` by `baseapp`'s `handleQueryCustom` method using `queryRoute`:
+[`Legacy queriers`](../building-modules/query-services.md#legacy-queriers) are very similar to `handlers`, except they serve user queries to the state as opposed to processing transactions. A [query](../building-modules/messages-and-queries.md#queries) is initiated from an [interface](#application-interface) by an end-user who provides a `queryRoute` and some `data`. The query is then routed to the correct application's `querier` by `baseapp`'s `handleQueryCustom` method using `queryRoute`:
 
 +++ https://github.com/cosmos/cosmos-sdk/blob/d9175200920e96bfa4182b5c8bc46d91b17a28a1/baseapp/abci.go#L388-L418
 
@@ -236,7 +236,7 @@ The SDK also provides a development endpoint to generate [Swagger](https://swagg
 
 #### Legacy API REST Endpoints
 
-The [module's Legacy REST interface](../building-modules/module-interfaces.md#rest) lets users generate transactions and query the state through REST calls to the application's Legacy API Service. REST routes are defined in a file `client/rest/rest.go`, which is composed of:
+The [module's Legacy REST interface](../building-modules/module-interfaces.md#legacy-rest) lets users generate transactions and query the state through REST calls to the application's Legacy API Service. REST routes are defined in a file `client/rest/rest.go`, which is composed of:
 
 - A `RegisterRoutes` function, which registers each route defined in the file. This function is called from the [main application's interface](#application-interfaces) for each module used within the application. The router used in the SDK is [Gorilla's mux](https://github.com/gorilla/mux).
 - Custom request type definitions for each query or transaction creation function that needs to be exposed. These custom request types build on the base `request` type of the Cosmos SDK: