Doc fixes

Small documentation fixes:
* Fix some typos
*  "*[RESTFUL](https://en.wikipedia.org/wiki/Representational_state_transfer)*" instead of "*RESTFULL*"
* Explain how to change refresh rate for web UI

The wiki also has a few typos (but I can not fix them):
* The page `The-Glances-RESTFULL-JSON-API` should be renamed `The-Glances-RESTFUL-JSON-API`
* *Serveur side* -> *Server side*

Happy new year !