Remove Windows icons

Discourages Windows usage.

_includes/sections/email-alternatives.html

@@ -8,7 +8,6 @@ meaning that you need-not inherently trust any entities like root certificate au
 website="https://bitmessage.org/"
 forum="https://forum.privacytools.io/t/discussion-bitmessage/661"
 github="https://github.com/Bitmessage/PyBitmessage"
-windows=""
 mac=""
 linux=""
 %}
@@ -20,7 +19,6 @@ description="Retroshare creates encrypted connections to your friends. Nobody ca
 website="https://retroshare.cc/"
 forum="https://forum.privacytools.io/t/discussion-retroshare/662"
 github="https://github.com/RetroShare/RetroShare"
-windows=""
 mac=""
 linux=""
 %}