update README

README.md

@@ -53,6 +53,24 @@ # Step 3: Clone the repository to your local machine, and install it.
 python setup.py install
 ```
 
+**Note:**
+
+- If already have Chrome, Chromium, or MS Edge installed, you can skip downloading Chromium by setting the environment variable
+`PUPPETEER_SKIP_CHROMIUM_DOWNLOAD` to `true`.
+
+- Some people are [having issues](https://github.com/mermaidjs/mermaid.cli/issues/15) installing this tool globally. Installing it locally is an alternative solution,
+
+    ```bash
+    npm install @mermaid-js/mermaid-cli
+    ```
+
+- don't forget to the configuration for mmdc in config.yml
+
+    ```yml
+    PUPPETEER_CONFIG: "./puppeteer-config.json"
+    MMDC: "./node_modules/.bin/mmdc"
+    ```
+
 ### Installation by Docker
 
 ```bash