Add closing script tag to example

Author: calumk

README.md

@@ -6,7 +6,7 @@ Add Mermaid and the plugin:
 
 ```html
 <script src="//unpkg.com/mermaid/dist/mermaid.js"></script>
-<script src="//unpkg.com/docsify-mermaid@latest/dist/docsify-mermaid.js"> 
+<script src="//unpkg.com/docsify-mermaid@latest/dist/docsify-mermaid.js"></script>
 <script>mermaid.initialize({ startOnLoad: true });</script>
 ```
 
@@ -21,4 +21,4 @@ Now you can include mermaid diagrams in your docsify docs:
 
 A demo is available on [Codepen](https://codepen.io/leward/project/editor/AyegJW).
 
-![Docsify with mermaid Screenshot](screenshot.png)
+![Docsify with mermaid Screenshot](screenshot.png)