Add installation instructions in case you don't have superuser access

There is the following text at the top of https://mosh.org:

You don't need to be the superuser to install or run Mosh

However it is unclear how to install mosh on server if you don't have root rights.

Could you, please, add instructions about installing mosh without root access. I think for now it can be just for one popular distribution, for exampe ubuntu.

Something like this gist: https://gist.github.com/xiaom/8264691 (code from gist doesn't work now, but there are some useful notes in comments, I think it would be very cool if you will accumulate these notes and publish remade gist on your site).

Thanks for excellent tool!

Inizia dal testo di installazione sul sito web di Mosh e esamina il gist collegato, inclusi i relativi commenti, alla ricerca di approcci che funzionino ancora senza root access. Il lavoro è completato quando il sito spiega una procedura di installazione di Ubuntu verificata per gli utenti senza superuser access.