To install Pandoc's manuals I run cabal install pandoc pandoc-citeproc as described in the manual.
I get nothing from man pandoc. 
Pandoc exists in brew but I would like to know how you get pandoc by manuals too. 
I would like to read man pandoc_markdown. 

How can you install pandoc with manuals?
There is pandoc --help as well as the online documentation/user guide. I have pandoc installed via Homebrew and I also have no man pages.

erik@Eriks-MBP:~$ man pandoc
No manual entry for pandoc