Add hermes parser (#17520)

packages/plugin-hermes/README.md

@@ -0,0 +1,27 @@
+# @prettier/plugin-hermes
+
+> Prettier [Hermes](https://github.com/facebook/hermes/blob/main/README.md) plugin.
+
+## Install
+
+```bash
+yarn add --dev prettier @prettier/plugin-hermes
+```
+
+## Usage
+
+Create or modify your [prettier configuration file](https://prettier.io/docs/en/configuration) to use the plugin:
+
+```json
+{
+  "overrides": [
+    {
+      "files": ["**/*.{js.flow,js,mjs,cjs}"],
+      "options": {
+        "plugins": ["@prettier/plugin-hermes"],
+        "parser": "hermes"
+      }
+    }
+  ]
+}
+```