Correct spelling; remove trailing whitespace

[jlapeyre]

• Correct a few spelling mistakes
• Remove trailing whitespace from lines (my code editors highlights these in yellow)
• Format the README for CLOPS. There were some indents that had no effect on rendering. Also, in the README, all sections had an intro sentence. One of them was not separated by a new line when rendered, although I think this was the intention.

[CLAassistant]

All committers have signed the CLA.