Corrected a typo and added 'code' blocks
Created by: RyuzakiKK
This is a small change to README.rst
Without the code block the commands in the section "From git" were all displayed in one line. I added it for every code snippets for consistency. I also added the "cd gnome-keyring" command for complete the install process.
And fixed the typo from "they" to "the".