Add note about the future of mixed_language_library (#1418)

Signed-off-by: Brentley Jones <[email protected]>

Author: brentleyjones

doc/rules.md

@@ -1000,6 +1000,10 @@ mixed_language_library(<a href="#mixed_language_library-name">name</a>, <a href=
 
 Creates a mixed language library from a Clang and Swift library target     pair.
 
+Note: In the future `swift_library` will support mixed-langauge libraries.
+Once that is the case, this macro will be deprecated.
+
+
 **PARAMETERS**
 
 

mixed_language/mixed_language_library.bzl

@@ -61,6 +61,9 @@ def mixed_language_library(
     """Creates a mixed language library from a Clang and Swift library target \
     pair.
 
+    Note: In the future `swift_library` will support mixed-langauge libraries.
+    Once that is the case, this macro will be deprecated.
+
     Args:
         name: The name of the target.
         alwayslink: If true, any binary that depends (directly or indirectly) on