Bug 1875444 - Remove last mention of libhyphen vendoring r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D199074

intl/hyphenation/README.mozilla

@@ -1,13 +0,0 @@
-About the hyphenation code in this directory
-============================================
-
-The hyphen directory comes from the Hyphen library, part of the hunspell project.
-  https://github.com/hunspell/hyphen
-
-This code is distributed under the GPL 2.0/LGPL 2.1/MPL 1.1 tri-license, as
-detailed in the associated README and COPYING files.
-
-Note that we do not include other tools and resources found in the complete
-Hyphen package from upstream, so the original README.* files may refer to
-additional files that are not present in the Mozilla source tree.
-