update readme

Author: wowbios

README.md

@@ -2,7 +2,7 @@
 Mermaid.js fluent api for .NET
 
 ## Roadmap
-1. Flowchart
+1. [Flowchart](https://mermaid-js.github.io/mermaid/#/flowchart)
    1. [Graph](https://mermaid-js.github.io/mermaid/#/flowchart?id=graph) :heavy_check_mark:
    2. [Orientation](https://mermaid-js.github.io/mermaid/#/flowchart?id=flowchart-orientation) :heavy_check_mark:
    3. [Shapes](https://mermaid-js.github.io/mermaid/#/flowchart?id=node-shapes) :heavy_check_mark: