update docs

README.md

@@ -159,12 +159,14 @@ Environment Variables
     * PORT: Server port. default: `3000`
     * ELASTICSEARCH_URI: URI to connect to Elasticearch.
     * REDIS_URI: URI to connect to Redis (use it as a session store instead of MongoDB).
-    * PLANTUML_URI: URI to connect to [PlantUML](http://plantuml.com/) server.
-    * BLOCKDIAG_URI: URI to connect to [blockdiag](http://http://blockdiag.com/) server.
     * PASSWORD_SEED: A password seed used by password hash generator.
     * SECRET_TOKEN: A secret key for verifying the integrity of signed cookies.
     * SESSION_NAME: The name of the session ID cookie to set in the response by Express. default: `connect.sid`
     * FILE_UPLOAD: `aws` (default), `local`, `none`
+* **Option to integrate with external systems**
+    * HACKMD_URI: URI to connect to [HackMD(CodiMD)](https://hackmd.io/) server.
+    * PLANTUML_URI: URI to connect to [PlantUML](http://plantuml.com/) server.
+    * BLOCKDIAG_URI: URI to connect to [blockdiag](http://http://blockdiag.com/) server.
 * **Option (Overwritable in admin page)**
     * OAUTH_GOOGLE_CLIENT_ID: Google API client id for OAuth login
     * OAUTH_GOOGLE_CLIENT_SECRET: Google API client secret for OAuth login
@@ -191,11 +193,11 @@ For development
 ### Build and Run the app
 
 1. `clone` this repository
-1. `yarn` to install all dependencies
+2. `yarn` to install all dependencies
     * DO NOT USE `npm install`
-1. `npm run build` to build client app
-1. `npm run server` to start the dev server
-1. Access `http://0.0.0.0:3000`
+3. `npm run build` to build client app
+4. `npm run server` to start the dev server
+5. Access `http://0.0.0.0:3000`
 
 Found a Bug?
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