[ci] Document that full git shas are required for manual prereleases (#34537)

Triggering the "(Runtime) Publish Prereleases Manual" workflow with a
short git sha doesn't work. It needs the full sha. We might be able to
make it work with the short sha as well, but for now we can at least
document the restriction.

Author: unstubbable

scripts/release/README.md

@@ -37,7 +37,7 @@ The high level process of creating releases is [documented below](#process). Ind
 If your code lands in the main branch, it will be automatically published to the prerelease channels within the next weekday. However, if you want to immediately publish a prerelease, you can trigger the job to run immediately via the GitHub UI:
 
 1. Wait for the commit you want to release to finish its [(Runtime) Build and Test workflow](https://github.com/facebook/react/actions/workflows/runtime_build_and_test.yml), as the prerelease script needs to download the build from that workflow.
-2. Copy the git sha of whichever commit you are trying to release
+2. Copy the full git sha of whichever commit you are trying to release
 3. Go to https://github.com/facebook/react/actions/workflows/runtime_prereleases_manual.yml
 4. Paste the git sha into the "Run workflow" dropdown
 5. Let the job finish and it will be released on npm