Fix example load directive. (#101)

rules/maprule_private.bzl

diff --git a/rules/maprule_private.bzl b/rules/maprule_private.bzl
index 007bfa5..ae44cf9 100644
--- a/rules/maprule_private.bzl
+++ b/rules/maprule_private.bzl
@@ -44,7 +44,7 @@
 _cmd_maprule_example = """
     # This file is //projects/game:BUILD
 
-    load("//tools/build_rules:maprule.bzl", "cmd_maprule")
+    load("@bazel_skylib//rules:maprule.bzl", "cmd_maprule")
 
     cmd_maprule(
         name = "process_assets",
@@ -77,7 +77,7 @@
 _bash_maprule_example = """
     # This file is //projects/game:BUILD
 
-    load("//tools/build_rules:maprule.bzl", "bash_maprule")
+    load("@bazel_skylib//rules:maprule.bzl", "bash_maprule")
 
     bash_maprule(
         name = "process_assets",