Switch to cfg = "exec" to fix buildifier failure (#129)

diff --git a/stardoc/stardoc.bzl b/stardoc/stardoc.bzl
index 21d5ca1..f5693fc 100644
--- a/stardoc/stardoc.bzl
+++ b/stardoc/stardoc.bzl
@@ -158,14 +158,14 @@
             doc = "The location of the stardoc tool.",
             allow_files = True,
             default = Label("//stardoc:stardoc"),
-            cfg = "host",
+            cfg = "exec",
             executable = True,
         ),
         "renderer": attr.label(
             doc = "The location of the renderer tool.",
             allow_files = True,
             default = Label("//stardoc:renderer"),
-            cfg = "host",
+            cfg = "exec",
             executable = True,
         ),
         "aspect_template": attr.label(
diff --git a/test/testdata/misc_apis_test/input.bzl b/test/testdata/misc_apis_test/input.bzl
index 63ea94a..925b698 100644
--- a/test/testdata/misc_apis_test/input.bzl
+++ b/test/testdata/misc_apis_test/input.bzl
@@ -49,7 +49,7 @@
             doc = "The location of the tool to use.",
             allow_files = True,
             default = Label("//foo/bar/baz:target"),
-            cfg = "host",
+            cfg = "exec",
             executable = True,
         ),
         "out": attr.output(