Improving synergy, Sidebar UI : add a support and a contribution link

Hi everyone ! First, thank a lot for this wonderful app 😄 Here is some ideas to improve

Problems :

• The button help only provide a glossary for Cesium.
• The button about, at home page has some useful link : Forum, Github...
• There is a Megadon that help newcomers/ starter and we don't know if that exist

Suggestions :

Improving visibility of all helpful links.

Add a button support in the sidebar with all possible helpful links for Users and Devs (icon chat bubble):

Users

• A link to ML chat group (telegram ?) or the forum ?
• The Forum : https://forum.monnaie-libre.fr/
• a website agregator about June (gmarché, airjune...) : https://infojune.fr

Devs

• Cesium git
• Duniter git
• Others git ?

Add a contribution button in the sidebar, (icon a heart) :

• a link to the Megadon and a button "request help/ or Starter Pack"
• a link to donation to support G1 server, dev and new paiement system (card, money...)

Thank a lot 🙂