Update docs to reflect per-thread default fontmap
Update docs to reflect per-thread default fontmap

Distrotech/pango,danny-ku/pango,danny-ku/pango,danny-ku/pango,Distrotech/pango,kari-lentz/alpha-pango,kari-lentz/alpha-pango,kari-lentz/alpha-pango,kari-lentz/alpha-pango,Distrotech/pango