Add favicon to maas documentation

[tbille]

There is no favicon on this project which makes it hard to find when you have 1000000 tabs open 😄

[jsseidel]

I'm using Chrome and I actually do see a favicon. This one, in fact: https://assets.ubuntu.com/v1/5922a009-maas-favicon-32px.png. Could your browser perhaps not be respecting the link? It appears in the page's code like this:

<link rel="icon" href="https://assets.ubuntu.com/v1/5922a009-maas-favicon-32px.png" type="image/x-icon" />

[tbille]

ok, by default https://docs.maas.io/ redirects me to the version 2.4 of the documentation by default which doesn't have a favicon.
While if I go on the version 2.5 it has one: https://docs.maas.io/2.5/en/

[jsseidel]

Ah. Makes sense. I will look into it.