Add markdown lint rules

Author: zaccari

.markdownlint.json

@@ -0,0 +1,8 @@
+{
+  "no-duplicate-heading": {
+    "siblings_only": true
+  },
+  "MD013": false,
+  "MD029": false,
+  "MD040": false
+}

proto/proto.bzl

@@ -1,7 +1,8 @@
-load("@bazel_skylib//lib:shell.bzl", "shell")
+""" Go rule to link generated proto Go files into workspace. """
+# load("@bazel_skylib//lib:shell.bzl", "shell")
 load("//:golink.bzl", "gen_copy_files_script")
 
-def go_proto_link_impl(ctx, **kwargs):
+def go_proto_link_impl(ctx, **_):
     return gen_copy_files_script(ctx, ctx.attr.dep[OutputGroupInfo].go_generated_srcs.to_list())
 
 _go_proto_link = rule(