Fix multi-line comments for cpp enums (#5345) (#5346)

- fix CSharp comments generation
- fix Python comments generation
- fix Lua comments generation
- fix PHP comments generation
- fix Dart comments generation
- add brief description of Color enum
- add multi-line comments to the Monster:Color

tests/MyGame/Example/Monster.lua

@@ -4,7 +4,7 @@
 
 local flatbuffers = require('flatbuffers')
 
--- /// an example documentation comment: monster object
+-- an example documentation comment: monster object
 local Monster = {} -- the module
 local Monster_mt = {} -- the class metatable
 
@@ -120,8 +120,8 @@ function Monster_mt:TestarrayofstringLength()
     end
     return 0
 end
--- /// an example documentation comment: this will end up in the generated code
--- /// multiline too
+-- an example documentation comment: this will end up in the generated code
+-- multiline too
 function Monster_mt:Testarrayoftables(j)
     local o = self.view:Offset(26)
     if o ~= 0 then