ref-manual/features.rst: drop ld-is-gold

Dropped in OE-Core after commit a4addb9ab630 ("recipes: Drop ld-is-gold
support").

(From yocto-docs rev: 95645cb765b20c3215defe165e7d886da98c1787)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/features.rst

@@ -167,9 +167,6 @@ metadata, as extra layers can define their own:
 -  *multiarch:* Enable building applications with multiple architecture
    support.
 
--  *ld-is-gold:* Use the :wikipedia:`gold <Gold_(linker)>`
-   linker instead of the standard GCC linker (bfd).
-
 -  *ldconfig:* Include support for ldconfig and ``ld.so.conf`` on the
    target.