* add links to extern section in manual (#5416)

* use tabs

std/haxe/extern/EitherType.hx

@@ -22,12 +22,14 @@
 package haxe.extern;
 
 /**
-    An abstract type allowing values to be either of `T1` or `T2` type.
-    Supports implicit casts from/to either types.
+	An abstract type allowing values to be either of `T1` or `T2` type.
+	Supports implicit casts from/to either types.
 
-    It is useful for interfacing with external code on dynamic platforms
-    such as JavaScript or Python.
+	It is useful for interfacing with external code on dynamic platforms
+	such as JavaScript or Python.
 
-    Otherwise, use of this type is discouraged.
+	Otherwise, use of this type is discouraged.
+	
+	@see <http://haxe.org/manual/lf-externs.html>
 **/
 abstract EitherType<T1,T2>(Dynamic) from T1 to T1 from T2 to T2 {}

std/haxe/extern/Rest.hx

@@ -23,10 +23,12 @@
 package haxe.extern;
 
 /**
-    A special abstract type that represents "rest" function argument.
+	A special abstract type that represents "rest" function argument.
 
-    Should be used as a type for the last argument of an extern method,
-    representing that arbitrary number of arguments of given type can be
-    passed to that method.
+	Should be used as a type for the last argument of an extern method,
+	representing that arbitrary number of arguments of given type can be
+	passed to that method.
+	
+	@see <http://haxe.org/manual/lf-externs.html>
 **/
 abstract Rest<T>(Array<T>) {}