Remove submodule section from README (belongs in release notes)

Author: bjornrobertsson

README.md

@@ -118,10 +118,3 @@ On macOS or Windows systems, we recommend using a VM or the provided `.devcontai
 - `test`: Runs tests.
 - `test-registry`: Stands up a local registry for caching images used in tests.
 - `docs/env-variables.md`: Updated the [environment variables documentation](./docs/env-variables.md).
-  
-**Submodule Handling Fix**
-
-An issue concerning git's submodule handling has been resolved through iterative refinements. This fix ensures robust submodule cloning and URL resolution without relying on the calls to the git binary (current fallback).
-```
-ENVBUILDER_GIT_CLONE_SUBMODULES=true
-```