Link to TLA+ community modules from Toolbox Help menu.

[Documentation][Toolbox]

org.lamport.tla.toolbox.doc/plugin.xml

@@ -166,6 +166,17 @@
             allPopups="false"
             locationURI="menu:toolbox.menu.help?before=toolbox.command.about">
          <menu id="community" label="Community" mnemonic="Y">
+	         <command
+	               commandId="org.lamport.tla.toolbox.doc.url"
+	               label="TLA+ CommunityModules"
+	               mnemonic="V"
+	               mode="FORCE_TEXT"
+	               style="push">
+	            <parameter
+	                  name="org.lamport.tla.toolbox.doc.url.name"
+	                  value="https://github.com/tlaplus/CommunityModules">
+	            </parameter>
+	         </command>
 	         <command
 	               commandId="org.lamport.tla.toolbox.doc.url"
 	               label="TLA+ user group"