Rewrote update_flash man page. Also included below details:   - Explaination of when temporary image is committed to permanent     side during firmware update.   - Information on -s and -n option.   - Added exit status.   - Added few examples.
Rewrote update_flash man page. Also included below details:
  - Explaination of when temporary image is committed to permanent
    side during firmware update.
  - Information on -s and -n option.
  - Added exit status.
  - Added few examples.

Requested-by: Paul Clarke <793d6d7c60bd6329d6f91fdb8c1b53aab99bf3da@us.ibm.com>
Signed-off-by: Vasant Hegde <a6d753843573f7bfed5075c1e875b0be8007a0ab@linux.vnet.ibm.com>

leitao/powerpc-ibm-utils-debian,shenki/powerpc-utils,leitao/powerpc-ibm-utils-debian,shenki/powerpc-utils,mdroth/powerpc-utils,tyreld/powerpc-utils,tyreld/powerpc-utils,kamalesh-babulal/powerpc-utils,shenki/powerpc-utils,tyreld/powerpc-utils,mdroth/powerpc-utils,leitao/powerpc-ibm-utils-debian,mdroth/powerpc-utils,kamalesh-babulal/powerpc-utils,kamalesh-babulal/powerpc-utils