chore: make markdown-link-check (celestiaorg#1957)

Makefile

@@ -72,7 +72,7 @@ build-docker:
 	$(DOCKER) build -t celestiaorg/celestia-app -f docker/Dockerfile .
 .PHONY: build-docker
 
-## lint: Run linters golangci-lint and markdownlint.
+## lint: Run all linters: golangci-lint, markdownlint, hadolint, yamllint.
 lint:
 	@echo "--> Running golangci-lint"
 	@golangci-lint run
@@ -85,6 +85,12 @@ lint:
 
 .PHONY: lint
 
+## markdown-link-check: Check all markdown links.
+markdown-link-check:
+	@echo "--> Running markdown-link-check"
+	@find . -name \*.md -print0 | xargs -0 -n1 markdown-link-check
+
+
 ## fmt: Format files per linters golangci-lint and markdownlint.
 fmt:
 	@echo "--> Running golangci-lint --fix"

README.md

@@ -87,6 +87,7 @@ See <https://docs.celestia.org/category/celestia-app> for more information
 1. Install [markdownlint](https://github.com/DavidAnson/markdownlint)
 1. Install [hadolint](https://github.com/hadolint/hadolint)
 1. Install [yamllint](https://yamllint.readthedocs.io/en/stable/quickstart.html)
+1. Install [markdown-link-check](https://github.com/tcort/markdown-link-check)
 
 ### Helpful Commands