try just changing it

Author: schacon

book/02-git-basics/sections/recording-changes.asc

@@ -366,7 +366,6 @@ index 8ebb991..643e24f 100644
  that highlights your work in progress (and note in the PR title that it's
 ----
 
-[[_git_difftool]]
 [NOTE]
 .Git Diff in an External Tool
 ====

book/C-git-commands/1-git-commands.asc

@@ -110,7 +110,7 @@ Finally, we use it to effectively compare submodule changes with `--submodule` i
 
 The `git difftool` command simply launches an external tool to show you the difference between two trees in case you want to use something other than the built in `git diff` command.
 
-We only briefly mention this in <<_git_difftool>>.
+We only briefly mention this in <<_git_diff_staged>>.
 
 ==== git commit