Documentation/HOWTO: info about interface changes should CC linux-api@vger

The "Documentation" section of this file mentions that when an interface
change is made, I should be CCed with info about the change (so that
man-pages can document it). Additionally request that this info be CCed
to the new [e-mail] list.

Signed-off-by: Michael Kerrisk <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/HOWTO

···
 When a kernel change causes the interface that the kernel exposes to
 userspace to change, it is recommended that you send the information or
 a patch to the manual pages explaining the change to the manual pages
-maintainer at [e-mail].
+maintainer at [e-mail], and CC the list
[e-mail].
 
 Here is a list of files that are in the kernel source tree that are
 required reading: