Replace ProtectedText with CryptPad (#726)

* Added CryptPad as one of the flagship productivity-tools, replacing protectedtext which is not open-source.

* modify CryptPad Productivity Tools description

* drop protected text

_includes/sections/selfhosted-cloud.html

@@ -33,3 +33,9 @@
   %}
 
 </div>
+
+<h3>Worth Mentioning</h3>
+<ul>
+  <li><a href="https://github.com/xwiki-labs/cryptpad/">CryptPad</a> - End-to-end encrypted real time collaboration sharing folders, media, and documents (open-source).</li>
+</ul>
+