README not up-to-date

[Jonathan Huot]

Hi,

Some sticky options are not described in README (text=raw), and the formatting itself leads to misinterpretation of the other options (e.g. hash= options are hidden in text).

I'm suggesting to change README as I did in branch below :

See README : https://github.com/thomsonreuters/nginx-sticky-module-ng/compare/readme-cleanup

See changes : https://github.com/thomsonreuters/nginx-sticky-module-ng/compare/readme-cleanup