remove DrawThe.Net (unmaintained since 2017) (#575)

- ref. https://github.com/awesome-foss/awesome-sysadmin/issues/405

README.md

@@ -251,7 +251,6 @@ Tools and scripts to support deployments to your servers.
 Tools used to create diagrams of networks, flows, etc.
 
 - [Diagrams.net](https://app.diagrams.net/) - A.K.A. [Draw.io](https://app.diagrams.net/). Easy to use Diagram UI with a plethora of templates. ([Source Code](https://github.com/jgraph/drawio)) `Apache-2.0` `JavaScript/Docker`
-- [DrawThe.Net](http://go.drawthe.net/) - Javascript tool that uses a YAML-formatted input to programmatically create large, complex, and visually solid diagrams. ([Source Code](https://github.com/cidrblock/drawthe.net)) `MIT` `JavaScript`
 - [Kroki](https://kroki.io) - API for generating diagrams from textual descriptions. ([Source Code](https://github.com/yuzutech/kroki)) `MIT` `Java`
 - [Mermaid](https://mermaid-js.github.io/mermaid-live-editor/) - Javascript module with a unique, easy, shorthand syntax. Integrates into several other tools like Grafana. ([Source Code](https://github.com/mermaid-js/mermaid-live-editor)) `MIT` `Nodejs/Docker`