Add documentation to ws_value_union_reinit()
Add missing memberof to documentation of ws_value_union_init_from_val()
Merge pull request #452 from neithernut/fix-value-union-documentation

Fix value union documentation
Add tex commands for building command list
Add short description about the section
Add command environment
Add command documentation: add
Add command documentation: sub
Split commands file into two subsections: regular/special commands