[Docs] Advise to wait after creating LTO commit (emscripten-core#20807)

Otherwise you might see the failure when you run `create_release.py` in
emsdk.

docs/process.md

@@ -92,6 +92,11 @@ How:
    [emscripten-releases][releases_repo] repo. When this CL is committed, let the
    resulting SHA be `<LTO-sha>`. An example of this CL is
    https://chromium-review.googlesource.com/c/emscripten-releases/+/3781978.
+   After landing the CL, wait for a couple hours before proceeding because
+   building and archiving for the new commit will take some time. Check
+   https://ci.chromium.org/p/emscripten-releases/g/main/console to see if the
+   commit has passed "Archive Binaries" phase for all three platforms and
+   additionally "Archive Binaries (arm64)" for Mac.
 1. Run [`scripts/create_release.py`][create_release_emsdk] in the emsdk
    repository. When we do both an LTO and a non-LTO release, run:
    ```