Add markdownlint in CI

Author: Adam Hughes

.circleci/config.yml

@@ -94,6 +94,20 @@ jobs:
           name: Check for Lint
           command: golangci-lint run ./...
 
+  lint_markdown:
+    <<: *defaults
+    docker:
+      - image: node:11
+    steps:
+      - attach_workspace:
+          at: /
+      - run:
+          name: Install markdownlint
+          command: npm install -g markdownlint-cli
+      - run:
+          name: Check for Lint
+          command: markdownlint -i vendor .
+
   unit_test:
     <<: *defaults
     steps:
@@ -124,6 +138,9 @@ workflows:
       - lint_source:
           requires:
             - get_source
+      - lint_markdown:
+          requires:
+            - get_source
       - unit_test:
           requires:
             - get_source

.markdownlint.json

@@ -0,0 +1,4 @@
+{
+    "default": true,
+    "MD013": false
+}

README.md

@@ -1,7 +1,7 @@
 # The Singularity Image Format (SIF)
 
 [![GoDoc](https://godoc.org/github.com/sylabs/sif?status.svg)](https://godoc.org/github.com/sylabs/sif)
-<a href="https://circleci.com/gh/sylabs/sif"><img src="https://circleci.com/gh/sylabs/sif.svg?style=shield&circle-token=7e762a71efecb4da6cd6981e90cf4cc9c5e4291e"/></a>
+[![Build Status](https://circleci.com/gh/sylabs/sif.svg?style=shield)](https://circleci.com/gh/sylabs/workflows/sif)
 [![Go Report Card](https://goreportcard.com/badge/github.com/sylabs/sif)](https://goreportcard.com/report/github.com/sylabs/sif)
 
 SIF is an open source implementation of the Singularity Container Image Format