add support for checking YAML and Markdown syntax

Author: kolomenkin

.config/.markdownlint.yaml

@@ -0,0 +1,15 @@
+# Manual for `.markdownlint.yaml` config:
+# https://github.com/DavidAnson/markdownlint#optionsconfig
+# Config file JSON schema:
+# https://github.com/DavidAnson/markdownlint/blob/main/schema/markdownlint-config-schema.json
+---
+default: true
+
+# Trailing spaces
+MD009:
+  br_spaces: 2
+
+# Line length
+MD013:
+  line_length: 140
+  tables: false

.config/.yamllint.yaml

@@ -0,0 +1,20 @@
+# Manual for `.yamllint.yaml` config:
+# https://yamllint.readthedocs.io/en/stable/configuration.html
+---
+extends: default
+
+yaml-files:
+  - '*.yaml'
+  - '*.yml'
+  - '.yamllint'
+
+rules:
+  line-length:
+    max: 120
+  brackets:
+    min-spaces-inside: 1
+    max-spaces-inside: 1
+  comments:
+    min-spaces-from-content: 1
+  new-lines:
+    type: unix

Makefile

@@ -0,0 +1,30 @@
+# =================================
+
+MARKDOWNLINT_CONFIG = ./.config/.markdownlint.yaml
+YAMLLINT_CONFIG     = ./.config/.yamllint.yaml
+
+# =================================
+
+check-all: check-md check-yaml
+
+# =================================
+
+check-md:
+# Using two slashes at the beginning of the paths for Windows bash shell
+	docker run --rm --tty --network=none --volume="${CURDIR}:/markdown:ro" \
+		--workdir=//markdown/ \
+		06kellyjac/markdownlint-cli:0.27.1-alpine \
+            --config=${MARKDOWNLINT_CONFIG} \
+            --ignore=./gtest/README.md \
+			-- ./
+
+check-yaml:
+# Using two slashes at the beginning of the paths for Windows bash shell
+	docker run --rm --tty --network=none --volume="$(CURDIR):/data:ro" \
+		--workdir=//data/ \
+		cytopia/yamllint:1.26-0.9 \
+            -c=${YAMLLINT_CONFIG} \
+			--strict \
+			-- ./
+
+# =================================