doc: Edit redundant use of file

Removed the word "file" after all the MDEF to avoid redundancy
Edited single line under overview folder in order to
gramatically correct the use of "file".

Change-Id: Ie785aa8c620f095fcd4171ef4efd2d056d6fa04b
Signed-off-by: Gerardo A. Aceves <gerardo.aceves@intel.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
11 files changed