Add softgen to projects that are using litellm (#16423)

* Add Softgen project documentation

* Add Softgen project to sidebars

* Update Softgen

docs/my-website/docs/projects/Softgen

@@ -0,0 +1,7 @@
+# Softgen
+
+`Softgen` is an AI-powered platform that builds full-stack web apps from your plain instructions.
+LiteLLM helps `Softgen` users to choose and use different LLMs.
+
+- [Softgen](https://softgen.ai)
+- [Academy](hhttps://academy.softgen.ai)

docs/my-website/sidebars.js

@@ -784,6 +784,7 @@ const sidebars = {
             "projects/GPTLocalhost",
             "projects/HolmesGPT",
             "projects/Railtracks",
+            "projects/Softgen",
           ],
         },
         "extras/code_quality",