Use actual announcement blog link, dochub not working (#102)

Author: zach-carr

source/index.txt

@@ -22,7 +22,7 @@ integration between MongoDB and Apache Spark.
    (versions 3.x and earlier) in parallel with version 10.x.
 
    To learn more about the new connector and its advantages, see the 
-   `MongoDB announcement blog post <https://dochub.mongodb.org/core/spark-connector-v10-announcement-blog>`__.
+   `MongoDB announcement blog post <https://www.mongodb.com/blog/post/new-mongodb-spark-connector>`__.
 
 With the connector, you have access to all Spark libraries for use with
 MongoDB datasets: Datasets for analysis with SQL (benefiting from