sysfs-namespaces: add a high-level Documentation file
sysfs-namespaces: add a high-level Documentation file

The first three paragraphs are almost verbatim taken from Eric's
commit message on the patch introducing network ns tags.  The next
two paragraphs I wrote to be a brief high level overview.  The last
section is taken from the commit message on "Implement sysfs tagged
directory support", but updated.  Hopefully correctly.

Signed-off-by: Serge E. Hallyn <dd6cacb2d07f0aa354aa6e74c149a3580e5a1db1@us.ibm.com>
Cc: Eric W. Biederman <8a741aa8cbd77ebc4a56ddb528ce9fd15d42f034@xmission.com>
Cc: Tejun Heo <546b05909706652891a87f7bfe385ae147f61f91@kernel.org>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@suse.de>


KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs