doc: mention long option abbreviation

* doc/coreutils.texi (Common options): Give example of
abbreviating options.
* THANKS: Update.
Reported by Adam Jimerson.

THANKS

@@ -10,6 +10,7 @@ the bug-report mailing list (as seen on last line of e.g., cp --help).
 A Costa                             agcosta@gis.net
 Aaron Hawley                        ashawley@uvm.edu
 Achim Blumensath                    blume@corona.oche.de
+Adam Jimerson                       vendion@charter.net
 Adam Klein                          aklein@debian.org
 Adrian Bunk                         bunk@stusta.de
 AIDA Shinra                         shinra@j10n.org

doc/coreutils.texi

@@ -673,8 +673,15 @@ program description.  For example, the @command{env} command's options
 must appear before its operands, since in some cases the operands
 specify a command that itself contains options.
 
+Most programs that accept long options recognize unambiguous
+abbreviations of those options.  For example, @samp{rmdir
+--ignore-fail-on-non-empty} can be invoked as @samp{rmdir
+--ignore-fail} or even @samp{rmdir --i}.  Ambiguous options, such as
+@samp{ls --h}, are identified as such.
+
 Some of these programs recognize the @option{--help} and @option{--version}
-options only when one of them is the sole command line argument.
+options only when one of them is the sole command line argument.  For
+these programs, abbreviations of the long options are not recognized.
 
 @table @samp