Update recording-changes.asc

Improve comment about what the '**' glob pattern does.

Author: chaitanyagurrapu

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

@@ -246,7 +246,7 @@ build/
 # ignore doc/notes.txt, but not doc/server/arch.txt
 doc/*.txt
 
-# ignore all .pdf files in the doc/ directory
+# ignore all .pdf files in the doc/ directory or in the sub directories of doc/
 doc/**/*.pdf
 ----