tools: clone proto files from spec (#6976)

## Description

clone proto files from spec in order to have them in a single location

closes tendermint/spec#343

CHANGELOG_PENDING.md

@@ -15,6 +15,7 @@ Special thanks to external contributors on this release:
   - [rpc] Remove the deprecated gRPC interface to the RPC service (@creachadair).
 
 - Apps
+  - [proto/tendermint] \#6976 Remove core protobuf files in favor of only housing them in the [tendermint/spec](https://github.com/tendermint/spec) repository.
 
 - P2P Protocol
 

CONTRIBUTING.md

@@ -109,7 +109,7 @@ We use [Protocol Buffers](https://developers.google.com/protocol-buffers) along
 
 For linting, checking breaking changes and generating proto stubs, we use [buf](https://buf.build/). If you would like to run linting and check if the changes you have made are breaking then you will need to have docker running locally. Then the linting cmd will be `make proto-lint` and the breaking changes check will be `make proto-check-breaking`.
 
-We use [Docker](https://www.docker.com/) to generate the protobuf stubs. To generate the stubs yourself, make sure docker is running then run `make proto-gen`.
+We use [Docker](https://www.docker.com/) to generate the protobuf stubs. To generate the stubs yourself, make sure docker is running then run `make proto-gen`. This command uses the spec repo to get the necessary protobuf files for generating the go code. If you are modifying the proto files manually for changes in the core data structures, you will need to clone them into the go repo and comment out lines 22-37 of the file `./scripts/protocgen.sh`.
 
 ### Visual Studio Code