Add Team chat section (#1067)

* Teamchat: initial commit

* teamchat: remove todo notes from cards

* nav.html: fix teamchat link

* assets: add icons for keybase & rocket.chat

* teamchat: add forum threads

* nav.html: change teamchat icon

* apply Jonah's suggestion on Keybase

* Jonah's & Nitrohorse's suggestions

* update keybase.png

* teamchat: delist mattermost

* teamchat: update description, add links

* update descriptions of apps

* fix keybase description

* teamchat: fix heading

* expand rocket.chat warning

* add missing the

* remove reduntant backslashes

* add teamchat to source_code.md

* small changes

* remove backslashes from link

* teamchat: add Wire Pro as worth mentioning

* remove excess '

_includes/sections/teamchat.html

@@ -0,0 +1,41 @@
+<h1 id="teamchat" class="anchor"><a href="#teamchat"><i class="fas fa-link anchor-icon"></i></a> Team chat applications where everything is end-to-end encrypted or under the control of your team administrator</h1>
+
+<div class="alert alert-warning" role="alert">
+        <strong>If your project currently uses a team chat like <a href="https://web.archive.org/web/20171029114027/https://feedback.discordapp.com/forums/326712-discord-dream-land/suggestions/17094256-implement-whispersystems-encryption-for-voice-and">Discord</a> or <a href="https://drewdevault.com/2015/11/01/Please-stop-using-slack.html">Slack</a> you should pick an alternative here.</strong>
+</div>
+
+{% include cardv2.html
+title="Rocket.chat"
+image="/assets/img/tools/rocket.chat.png"
+description="Rocket.chat is an self-hostable open source platform for team communication. It has optional federation and experimental E2EE. <a href=\"https://rocket.chat/docs/user-guides/end-to-end-encryption/\"><span class=\"badge badge-warning\" data-toggle=\"tooltip\" title=\"The documentation says this of E2EE: 'Note: This feature is currently in alpha. It's also not yet supported on mobile'. There is no forward secrecy so compromised decryption password would leak all messages. The federation was also added afterwards potentially causing room for mistakes.'\">Experimental <i class=\"far fa-question-circle\"></i></a></span>"
+website="https://rocket.chat/"
+forum="https://forum.privacytools.io/t/discussion-rocket-chat/1223"
+github="https://github.com/rocketchat/"
+android=""
+ios=""
+mac=""
+windows=""
+linux=""
+%}
+
+{% include cardv2.html
+title="Keybase"
+image="/assets/img/tools/keybase.png"
+description='Keybase provides a hosted team chat with end-to-end encryption. It has also been <a href="https://keybase.io/docs-assets/blog/NCC_Group_Keybase_KB2018_Public_Report_2019-02-27_v1.3.pdf">indepedently audited (PDF)</a>. <span class="badge badge-warning" data-toggle="tooltip" title="The server side of Keybase runs on proprietary code and is centralized">experimental <i class="far fa-question-circle"></i> (<a href="https://github.com/keybase/client/issues/6374">GitHub issue</a>)</span>'
+website="https://keybase.io/"
+forum="https://forum.privacytools.io/t/discussion-keybase/1224"
+github="https://github.com/Keybase"
+android=""
+ios=""
+mac=""
+windows=""
+linux=""
+web=""
+%}
+
+
+<h3>Worth Mentioning</h3>
+
+<ul>
+  <li><a href="https://wire.com/en/products/pro-secure-team-collaboration/">Wire Pro</a> - Paid team communication with E2EE. <span class="badge badge-warning" data-toggle="tooltip" title="The Privacytools.io team has no experience with Wire Pro, while we can recommend the free version.">Untested<i class="far fa-question-circle"></i></span></li>
+</ul>