Add markdown linting

Signed-off-by: Brandon Mitchell <git@bmitch.net>

.markdownlint.yml

@@ -0,0 +1,19 @@
+# all lists use a `-`
+MD004:
+  style: dash
+
+# allow tabs in code blocks (for Go)
+MD010:
+  code_blocks: false
+
+# disable line length, prefer one sentence per line for PRs
+MD013: false
+
+# emphasis with underscore (`_emphasis_`)
+MD049:
+  style: "underscore"
+
+# bold with asterisk (`**bold**`)
+MD050:
+  style: "asterisk"
+    

CODE_OF_CONDUCT.md

@@ -18,23 +18,23 @@ diverse, inclusive, and healthy community.
 Examples of behavior that contributes to a positive environment for our
 community include:
 
-* Demonstrating empathy and kindness toward other people
-* Being respectful of differing opinions, viewpoints, and experiences
-* Giving and gracefully accepting constructive feedback
-* Accepting responsibility and apologizing to those affected by our mistakes,
+- Demonstrating empathy and kindness toward other people
+- Being respectful of differing opinions, viewpoints, and experiences
+- Giving and gracefully accepting constructive feedback
+- Accepting responsibility and apologizing to those affected by our mistakes,
   and learning from the experience
-* Focusing on what is best not just for us as individuals, but for the overall
+- Focusing on what is best not just for us as individuals, but for the overall
   community
 
 Examples of unacceptable behavior include:
 
-* The use of sexualized language or imagery, and sexual attention or advances of
+- The use of sexualized language or imagery, and sexual attention or advances of
   any kind
-* Trolling, insulting or derogatory comments, and personal or political attacks
-* Public or private harassment
-* Publishing others' private information, such as a physical or email address,
+- Trolling, insulting or derogatory comments, and personal or political attacks
+- Public or private harassment
+- Publishing others' private information, such as a physical or email address,
   without their explicit permission
-* Other conduct which could reasonably be considered inappropriate in a
+- Other conduct which could reasonably be considered inappropriate in a
   professional setting
 
 ## Enforcement Responsibilities

Makefile

@@ -14,8 +14,9 @@ GO_BUILD_FLAGS=-ldflags "$(LD_FLAGS)" -tags nolegacy
 DOCKERFILE_EXT:=$(shell if docker build --help 2>/dev/null | grep -q -- '--progress'; then echo ".buildkit"; fi)
 DOCKER_ARGS=--build-arg "VCS_REF=$(VCS_REF)"
 GOPATH:=$(shell go env GOPATH)
+PWD:=$(shell pwd)
 
-.PHONY: all fmt vet test vendor binaries docker artifacts artifact-pre plugin-user plugin-host .FORCE
+.PHONY: all fmt vet test lint lint-go lint-md vendor binaries docker artifacts artifact-pre plugin-user plugin-host .FORCE
 
 .FORCE:
 
@@ -30,9 +31,15 @@ vet:
 test:
 	go test -cover ./...
 
-lint: $(GOPATH)/bin/staticcheck
+lint: lint-go lint-md
+
+lint-go: $(GOPATH)/bin/staticcheck .FORCE
 	$(GOPATH)/bin/staticcheck -checks all ./...
 
+lint-md: .FORCE
+	docker run --rm -v "$(PWD):/workdir:ro" ghcr.io/igorshubovych/markdownlint-cli:latest \
+	  --ignore vendor .
+
 vendor:
 	go mod vendor
 

docs/README.md

@@ -88,7 +88,7 @@ The following functions have been added in addition to the defaults available in
    Experimentally, the API call has been added to take a token and run the tag delete against `hub.docker.com` instead of `docker.io`.
    To implement this, add the following section to the `~/.regctl/config.json`:
 
-   ```json
+   ```jsonc
    {
      "hosts": {
        "hub.docker.com": {
@@ -108,11 +108,11 @@ The following functions have been added in addition to the defaults available in
 
    A: If your `$HOME/.docker/config.json` includes a section like the following:
 
-   ```json
+   ```jsonc
    "credHelpers": {
       "gcr.io": "gcr", 
       "public.ecr.aws": "ecr-login", 
-   },
+   }
    ```
 
    These will work with standalone binaries or with the alpine image variants.