reword one unclear sentence

suggested by @HonkingGoose and @ben

book/07-git-tools/sections/submodules.asc

@@ -682,7 +682,7 @@ CONFLICT (submodule): Merge conflict in DbConnector
 Automatic merge failed; fix conflicts and then commit the result.
 ----
 
-What it's suggesting that you do is to update the index like you had run `git add`, which clears the conflict, then commit.
+The suggested command Git is providing will update the index as though you had run `git add` (which clears the conflict), then commit.
 You probably shouldn't do this though.
 You can just as easily go into the submodule directory, see what the difference is, fast-forward to this commit, test it properly, and then commit it.