Update release docs to work around file watcher race condition. (pant…

…sbuild#21081)

The start_release.py script modifies workspace files, 
and so will race with the file watcher to complete before 
being killed and restarted. And since the process is not
idempotent (e.g., it creates a local git branch) that restarted
process can fail.

docs/docs/contributions/releases/release-process.mdx

@@ -77,7 +77,7 @@ The release commit is the commit that bumps the VERSION string. For `dev`/`a0` r
 
 ### Bump the VERSION
 
-From the `main` branch, run `pants run src/python/pants_release/start_release.py -- --new 2.9.0.dev1 --release-manager your_github_username --publish` with the relevant version and your own GitHub username.
+From the `main` branch, run `pants --no-watch-filesystem --no-pantsd run src/python/pants_release/start_release.py -- --new 2.99.0.dev1 --release-manager your_github_username --publish` with the relevant version and your own GitHub username.
 
 This will create a pull request that: