Added clarification about repo re-initialization

Author: josh-byster

book/04-git-server/sections/git-on-a-server.asc

@@ -54,7 +54,7 @@ $ git clone [email protected]:/srv/git/my_project.git
 
 If a user SSHs into a server and has write access to the `/srv/git/my_project.git` directory, they will also automatically have push access.
 
-Git will automatically add group write permissions to a repository properly if you run the `git init` command with the `--shared` option.(((git commands, init, bare)))
+Git will automatically add group write permissions to a repository properly if you run the `git init` command with the `--shared` option. Note that by running this command, you will not destroy any commits, refs, etc. in the process.(((git commands, init, bare)))
 
 [source,console]
 ----