Improve Proc.call documentation

* Clarify variable names
* Add markup around inline example
* Reordered examples to match descriptions
Thanks for the tips! While I agree with saying 'given parameters' rather than 'parameters given', I feel that is a separate issue than the changes in the current commits--same with whitespace cleanup. Determining whether there should be one or two spaces after a double stop should be a separate issue or pull request that addresses general style.

As for 'syntactic sugar', I think that 'syntax sugar' is a little simpler and easier to understand, as well as more idiomatic. (/c @drbrain)