Doc: treewide : Fix typos in DocBook/filesystem.xml

This patch fix spelling typos found in DocBook/filesystem.xml.
It is because the file was generated from comments in code,
I have to fix the comments in codes, instead of xml file.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index 7f277e4..76579c28 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -304,7 +304,7 @@
  * Locate any valid recovery information from the journal and set up the
  * journal structures in memory to ignore it (presumably because the
  * caller has evidence that it is out of date).
- * This function does'nt appear to be exorted..
+ * This function doesn't appear to be exported..
  *
  * We perform one pass over the journal to allow us to tell the user how
  * much recovery information is being erased, and to let us initialise