protocol/README: incorrect instructions for testing with a local cosmos-sdk or cometbft fork

[SheldonHolmgren]

protocol/README.md suggests inserting the following replace directive in go.mod

	github.com/cosmos/cosmos-sdk v0.47.0-alpha2 => /Users/bryce/projects/cosmos-sdk

in order to test with a local fork of cosmos-sdk. However, that won't work because the docker container cannot access that path.

My workaround has been the following:

1. Create a new subdirectory protocol/my_forks
2. Clone dydx's forks of cosmos-sdk, cometbft and iavl into that subdirectory
3. Add the new subdirectory to .gitignore
4. Mount the new subdirectory in the Dockerfile:

diff --git a/protocol/Dockerfile b/protocol/Dockerfile
index e7246444..868c820b 100644
--- a/protocol/Dockerfile
+++ b/protocol/Dockerfile
@@ -20,6 +20,7 @@ WORKDIR /dydxprotocol
 COPY go.* ./
 RUN --mount=type=cache,target=/root/.cache/go-build \
     --mount=type=cache,target=/root/go/pkg/mod \
+    --mount=type=bind,source=my_forks,dst=/dydxprotocol/my_forks,ro \
     go mod download

If that sounds like the right approach, I will create a PR that updates the README. I'm not doing that yet because I'm a newcomer to both the dydx and docker and there might be a smarter way.

[linear]

GH-29 protocol/README: incorrect instructions for testing with a local cosmos-sdk or cometbft fork