Use python syntax for starlark

Summary:
Since in prismjs, it doesn't support starlark syntax highlight. https://github.com/PrismJS/prism/tree/master/components
We use python syntax instead.

Reviewed By: stepancheg

Differential Revision: D66912196

fbshipit-source-id: bae4626ff124bd6ac4619b18dd753b46ab439283

starlark/src/docs/parse.rs

@@ -43,7 +43,7 @@ pub enum DocStringKind {
     /// For functions, they are the piece in `"""` that come right after the `def foo():` line,
     /// and they have sections for additional details. An example from a starlark file might be:
     ///
-    /// ```starlark
+    /// ```python
     /// """ Module level docs here """
     ///
     /// def some_function(val: "string") -> "string":