chore(dotnet): generate IDownload.createReadStream method (#6192)

docs/src/api/class-download.md

@@ -55,7 +55,7 @@ not performed and user has no access to the downloaded files.
 :::
 
 ## async method: Download.createReadStream
-* langs: java, js
+* langs: java, js, csharp
 - returns: <[null]|[Readable]>
 
 Returns readable stream for current download or `null` if download failed.

utils/doclint/generateDotnetApi.js

@@ -98,6 +98,7 @@ const customTypeNames = new Map([
   classNameMap.set('path', 'string');
   classNameMap.set('URL', 'string');
   classNameMap.set('RegExp', 'Regex');
+  classNameMap.set('Readable', 'Stream');
 
   // this are types that we don't explicility render even if we get the specs
   const ignoredTypes = ['TimeoutException'];