Turns out that /proc has official documentation and people even trying
to keep it uptodate.
Link: http://lkml.kernel.org/r/20181116134630.GA8004@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 F:     fs/proc/
 F:     include/linux/proc_fs.h
 F:     tools/testing/selftests/proc/
+F:     Documentation/filesystems/proc.txt
 
 PROC SYSCTL
 M:     Luis Chamberlain <mcgrof@kernel.org>