Move Bitmessage to peer-to-peer RTC. Move I2P-Bote to Self contained networks. Remove "email alternatives" page. (#1559)

- Move I2P-Bote to Self contained networks.
- Remove "email alternatives" page and nav item

_includes/sections/self-contained-networks.html

@@ -63,6 +63,7 @@ github="https://github.com/freenet/"
 <ul>
   <li><a href="https://zeronet.io/">ZeroNet</a> - Open, free, and uncensorable websites, using Bitcoin cryptography and BitTorrent network. <span class="badge badge-danger" data-toggle="tooltip" title="Your IP address isn't hidden by default and won't be, unless you enforce Tor usage.">privacy warning <span class="far fa-question-circle"></span></span></li>
   <li><a href="https://retroshare.cc/">RetroShare</a> - An open source, cross-platform, friend-to-friend, secure, and decentralized communication platform.</li>
+  <li><a href="https://i2pbote.xyz/">I2P-Bote</a> - End-to-end encrypted decentralized mail system within the I2P network.</li>
   <li><a href="https://gnunet.org/">GNUnet</a> - GNUnet provides a strong foundation of free software for a global, distributed network that provides security and privacy.</li>
   <li><a href="https://ipfs.io/">IPFS</a> <em>and</em> <a href="https://github.com/ipfs-shipyard/ipfs-companion">IPFS Companion</a>- A peer-to-peer hypermedia protocol to make the web faster, safer, and more open. IPFS Companion is a browser extension for redirecting queries to a gateway of your choice (generally local). <a href="https://github.com/privacytoolsIO/privacytools.io/pull/361#issuecomment-344414022">
     <span class="badge badge-danger" data-toggle="tooltip" title="">