Commit: LD: Document use of SOURCE_DATE_EPOCH in Environment section

[Nick Clifton]

Hi Guys,

  I am applying the patch below to update the linker's documentation,
  adding an entry to the Environment Variables section mentioning the
  potential use of the SOURCE_DATE_EPOCH variable.  (Something that I
  should have done when I added the code to use SOURCE_DATE_EPOCH in the
  first place, but I forgot).

Cheers
  Nick

diff --git a/ld/ld.texi b/ld/ld.texi
index 89e3913317a..24dcf9db919 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -4048,6 +4048,13 @@ a similar fashion by the @code{gcc} linker wrapper program.  The default
 may be overridden by the @samp{--demangle} and @samp{--no-demangle}
 options.
 
+@kindex SOURCE_DATE_EPOCH
+@cindex timestamps
+If the PE/COFF specific @option{--insert-timestamp} is active and the
+@env{SOURCE_DATE_EPOCH} environment variable is defined, then the
+timestamp value in this variable will be inserted into the COFF header
+instead of the current time.
+
 @c man end
 @end ifset