Documentation: remove duplicated words

Remove many duplicated words under Documentation/ and do other small
cleanups.

Examples:
        "and and" --> "and"
        "in in" --> "in"
        "the the" --> "the"
        "the the" --> "to the"
        ...

Signed-off-by: Paolo Ornati <ornati@fastwebnet.it>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/filesystems/files.txt b/Documentation/filesystems/files.txt
index 8c206f4..133e213 100644
--- a/Documentation/filesystems/files.txt
+++ b/Documentation/filesystems/files.txt
@@ -55,7 +55,7 @@
 2. Reading of the fdtable as described above must be protected
    by rcu_read_lock()/rcu_read_unlock().
 
-3. For any update to the the fd table, files->file_lock must
+3. For any update to the fd table, files->file_lock must
    be held.
 
 4. To look up the file structure given an fd, a reader