Update for latest diagnostics and lints (#6552)

Content reviewed  already within the SDK.

Author: parlough

src/_data/linter_rules.json

@@ -1030,7 +1030,7 @@
   },
   {
     "name": "discarded_futures",
-    "description": "Don't invoke asynchronous functions in non-`async` blocks.",
+    "description": "There should be no `Future`-returning calls in synchronous functions unless they are assigned or returned.",
     "categories": [
       "errorProne"
     ],