doc: output correct --help references with --program-prefix

* src/system.h (emit_ancillary_info): Take the invariant PROGRAM_NAME
as a parameter, so that consistent references are made to online docs
and texinfo nodes, when a --program-prefix is in place.  Note the
man pages don't need this fix as they're generated before the program
prefix is used.
* NEWS: Mention the improvements in references to online documentation.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/ptx.c b/src/ptx.c
index 39ac5e4b0..c1429ebc6 100644
--- a/src/ptx.c
+++ b/src/ptx.c
@@ -1858,7 +1858,7 @@ Output a permuted index, including context, of the words in the input files.\n\
 \n\
 With no FILE, or when FILE is -, read standard input.  Default is '-F /'.\n\
 "), stdout);
-      emit_ancillary_info ();
+      emit_ancillary_info (PROGRAM_NAME);
     }
   exit (status);
 }