Lint markdown in CI (#5645)

docs/ManualMocks.md

@@ -28,7 +28,7 @@ other than the project root) and will be **automatically** mocked. There's no
 need to explicitly call `jest.mock('module_name')`.
 
 Scoped modules can be mocked by creating a file in a directory structure that
-matches the name of the scoped module.  For example, to mock a scoped module
+matches the name of the scoped module. For example, to mock a scoped module
 called `@scope/project-name`, create a file at
 `__mocks__/@scope/project-name.js`, creating the `@scope/` directory
 accordingly.

package.json

@@ -85,11 +85,12 @@
     "jest-coverage": "yarn jest --coverage",
     "lint": "eslint . --cache --ext js,md",
     "lint-es5-build": "eslint --no-eslintrc --no-ignore --env=browser packages/*/build-es5",
-    "lint:md": "prettier docs/**/*.md packages/*/README.md packages/*/docs/**/*.md website/blog/*.md .github/*.md CHANGELOG.md CONTRIBUTING.md website/README.md README.md --write",
+    "lint:md": "prettier '**/*.md' --write",
+    "lint:md:ci": "prettier '**/*.md' --list-different",
     "postinstall": "yarn build",
     "publish": "yarn build-clean && yarn build && lerna publish --silent",
     "test-ci-es5-build-in-browser": "karma start --single-run",
-    "test-ci": "yarn typecheck && yarn lint && yarn lint-es5-build && yarn jest-coverage -- -i && node scripts/mapCoverage.js && codecov",
+    "test-ci": "yarn typecheck && yarn lint && yarn lint-es5-build && yarn lint:md:ci && yarn jest-coverage -i && node scripts/mapCoverage.js && codecov",
     "test-ci-partial": "yarn jest -i",
     "test-pretty-format-perf": "node packages/pretty-format/perf/test.js",
     "test": "yarn typecheck && yarn lint && yarn jest",