Docs: formatting and clarifications

 - https://hibernate.atlassian.net/browse/HSEARCH-1670
 - https://hibernate.atlassian.net/browse/HSEARCH-1671

sorry I meant to explain that, apparently I didn't.
Yes there are two problems with using '+' : 
 - the formatting it used to apply is no longer applied, usage of backticks still works fine
 - somehow it prevents substitutions from happening, for example we'd have literal {hibernateSearchVersion} in our rendered output rather than have it replaced with the version number.

Essentially I've run a replace-all, but then manually verifying I wouldn't accidentally replace a legitimate usage of '+'.
By doing so I also found a couple of typos and formatting mistakes, like unmatched close of '+' which was causing some odd renderings here and there.