be more precise

Author: sabine

CONTRIBUTING.md

@@ -279,6 +279,6 @@ Feel free to use any approach while creating a PR. Here are a few suggestions fr
 
 ## Troubleshooting
 
-### After rebase, my branch doesn't build anymore
+### After rebase on `main`, my branch doesn't build anymore
 
-Please check in the commit log whether an upgrade of the dependencies (advancing of the `opam-repository` commit hash) has happened. If this is the case, running `dune pkg lock` should install the new dependencies.
+Please check in the commit log (`git log`) whether an upgrade of the dependencies (advancing of the `opam-repository` commit hash) has happened. If this is the case, running `dune pkg lock` should install the new dependencies.