Added a README about the custom font-datatracker font library, and how to add glyphs to it.

 - Legacy-Id: 18735

Author: levkowetz

ietf/static/ietf/font-datatracker/README

@@ -0,0 +1,14 @@
+This directory contains files for a webfont generated by http://fontello.com
+open source project.  It contains 2 glyphs not readily available in the font
+libraries used in the datatracker:  A Meetecho glyph and a Groupd glyph that
+communicates group conference better.  These are both used in the link lists
+on the IETF agenda page.
+
+To add more glyphs, follow the instructions available at
+https://github.com/fontello/fontello/wiki/How-to-save-and-load-projects.  The
+config.json file in the same directory as this README file contains all the
+information needed by fontello to set up things so that you can continue
+working, to add new glyphs for instance.
+
+
+        Henrik, 05 Dec 2020