Upgrade clients upgrading menu, and english tips spelling corrected.

Updated a client menu, so now it's possible to earn client start money and happiness points.

Corrected some spelling mistakes in english tips. 
I'm not native speaker, and i'm dyslexic so it was hard for me to learn good spelling in my nativ (polish) speach, i done it so i will try to do so in english. And i will also try no to make any spelling mistakes in future by using google translate more often.