Adds missing `code-block` to macros' docstrings.

lib/core/macros.nim

@@ -268,6 +268,8 @@ proc quote*(bl: stmt, op = "``"): PNimrodNode {.magic: "QuoteAst".}
   ##
   ## Example:
   ##   
+  ## .. code-block:: nimrod
+  ##
   ##   macro check(ex: expr): stmt =
   ##     # this is a simplified version of the check macro from the
   ##     # unittest module.
@@ -290,6 +292,8 @@ template emit*(e: expr[string]): stmt =
   ## that should be inserted verbatim in the program
   ## Example:
   ##
+  ## .. code-block:: nimrod
+  ##
   ##   emit("echo " & '"' & "hello world".toUpper & '"')
   ##
   eval: result = e.parseStmt