Update PyPI description and README

(cherry picked from commit 7db156a)

Author: deliahu

pkg/workloads/cortex/client/README.md

@@ -1 +1 @@
-Deploy machine learning models to production - [cortex.dev](https://www.cortex.dev)
+Deploy machine learning models to production - [docs.cortex.dev](https://www.docs.cortex.dev)

pkg/workloads/cortex/client/setup.py

@@ -79,7 +79,7 @@ def run(self):
 setup(
     name="cortex",
     version="0.24.0",  # CORTEX_VERSION
-    description="Model serving at scale",
+    description="Deploy machine learning models to production",
     author="cortex.dev",
     author_email="dev@cortex.dev",
     license="Apache License 2.0",