gnu: font-gnu-freefont: Add otf and woff font types.

* gnu/packages/fonts.scm (font-gnu-freefont): Add otf and woff font types.
* gnu/packages/genealogy.scm (gramps)[inputs]: Replace font-gnu-freefont-tff
with font-gnu-freefont.
* doc/guix.texi: Adjust a reference to the package.

Signed-off-by: Leo Famulari <leo@famulari.name>