KT-5512 Update Any docs

 #KT-5512 Fixed
KT-1720 "Type-safe Groovy-style builders" wiki page appears to be out of date
 #KT-1720 Fixed
KT-592 Please add auto-cast in expressions example to documentation
 #KT-592 Fixed
KT-2383 Add description of the syntax for visibility modifiers for constructor to documentation
 #KT-2383 Fixed
Merge pull request #77 from JetBrains/fixes

Fixes for some issues from YouTrack