Simplify sort_link code examples in README docs.
Simplify sort_link code examples in README docs.

[skip ci]

martndemus/ransack,mariorcardoso/ransack,johan--/ransack,Mario245/ransack,laserlemon/ransack,outstand/ransack,avit/ransack,vaski/ransack,nagyt234/ransack,Eric-Guo/ransack,guilleva/ransack,reinteractive/ransack,amboxer21/ransack,roman-franko/ransack,activerecord-hackery/ransack,AndrewSwerlick/ransack