[glibc/release/2.34/master] manual: Clarify that abbreviations of long options are allowed

[Siddhesh Poyarekar <siddhesh@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=31af92b9c8cf753992d45c801a855a02060afc08

commit 31af92b9c8cf753992d45c801a855a02060afc08
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date:   Wed May 4 15:56:47 2022 +0530

    manual: Clarify that abbreviations of long options are allowed
    
    The man page and code comments clearly state that abbreviations of long
    option names are recognized correctly as long as they are unique.
    Document this fact in the glibc manual as well.
    
    Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
    Reviewed-by: Florian Weimer <fweimer@redhat.com>
    Reviewed-by: Andreas Schwab <schwab@linux-m68k.org>
    (cherry picked from commit db1efe02c9f15affc3908d6ae73875b82898a489)

Diff:
---
 manual/getopt.texi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/manual/getopt.texi b/manual/getopt.texi
index 5485fc4694..b4c0b15ac2 100644
--- a/manual/getopt.texi
+++ b/manual/getopt.texi
@@ -250,7 +250,8 @@ option, and stores the option's argument (if it has one) in @code{optarg}.
 
 When @code{getopt_long} encounters a long option, it takes actions based
 on the @code{flag} and @code{val} fields of the definition of that
-option.
+option.  The option name may be abbreviated as long as the abbreviation is
+unique.
 
 If @code{flag} is a null pointer, then @code{getopt_long} returns the
 contents of @code{val} to indicate which option it found.  You should