tools: update eslint-plugin-markdown configuration

This commit updates the linting setup to work with
eslint-plugin-markdown@2.0.0. This also allows the update-eslint
script to continue to function properly without changes.

.eslintrc.js

@@ -53,12 +53,12 @@ module.exports = {
   overrides: [
     {
       files: [
-        'doc/api/esm.md',
-        'doc/api/fs.md',
-        'doc/api/module.md',
-        'doc/api/modules.md',
-        'doc/api/packages.md',
-        'doc/api/wasi.md',
+        'doc/api/esm.md/*.js',
+        'doc/api/fs.md/*.js',
+        'doc/api/module.md/*.js',
+        'doc/api/modules.md/*.js',
+        'doc/api/packages.md/*.js',
+        'doc/api/wasi.md/*.js',
         'test/es-module/test-esm-type-flag.js',
         'test/es-module/test-esm-type-flag-alias.js',
         '*.mjs',
@@ -68,6 +68,10 @@ module.exports = {
     },
     {
       files: ['**/*.md'],
+      processor: 'markdown/markdown',
+    },
+    {
+      files: ['**/*.md/*.js'],
       parserOptions: { ecmaFeatures: { impliedStrict: true } },
       rules: { strict: 'off' },
     },

Makefile

@@ -1209,7 +1209,7 @@ lint-md: lint-js-doc | tools/.mdlintstamp
 LINT_JS_TARGETS = .eslintrc.js benchmark doc lib test tools
 
 run-lint-js = tools/node_modules/eslint/bin/eslint.js --cache \
-	--report-unused-disable-directives --ext=$(EXTENSIONS) $(LINT_JS_TARGETS)
+	--report-unused-disable-directives $(LINT_JS_TARGETS)
 run-lint-js-fix = $(run-lint-js) --fix
 
 .PHONY: lint-js-fix
@@ -1220,8 +1220,6 @@ lint-js-fix:
 .PHONY: lint-js-doc
 # Note that on the CI `lint-js-ci` is run instead.
 # Lints the JavaScript code with eslint.
-lint-js lint-js-fix: EXTENSIONS=.js,.mjs,.md
-lint-js-doc: EXTENSIONS=.md
 lint-js lint-js-doc:
 	@if [ "$(shell $(node_use_openssl))" != "true" ]; then \
 		echo "Skipping $@ (no crypto)"; \
@@ -1234,7 +1232,7 @@ jslint: lint-js
 	$(warning Please use lint-js instead of jslint)
 
 run-lint-js-ci = tools/node_modules/eslint/bin/eslint.js \
-  --report-unused-disable-directives --ext=.js,.mjs,.md -f tap \
+  --report-unused-disable-directives -f tap \
 	-o test-eslint.tap $(LINT_JS_TARGETS)
 
 .PHONY: lint-js-ci