docs: improve swagger

- use markdown files in swagger
- automate version, use swager.conf template
- embed swagger ui index.html as docs.html

docs/index.go

@@ -1,3 +1,9 @@
 package docs
 
-import _ "github.com/swaggo/swag" // make sure swag is in go.mod
+import (
+	_ "embed"
+        _ "github.com/swaggo/swag" // make sure swag is in go.mod
+)
+
+//go:embed docs.html
+var DocsHTML []byte