docs: Remove disclaimer that datafusion 50.0.0 is not released (#17695)

* docs: Remove disclaimer that datafusion 50.0.0 is not released

* Add section about 51.0.0

Author: nuno-faria

docs/source/library-user-guide/upgrading.md

@@ -19,10 +19,13 @@
 
 # Upgrade Guides
 
-## DataFusion `50.0.0`
+## DataFusion `51.0.0`
+
+**Note:** DataFusion `51.0.0` has not been released yet. The information provided in this section pertains to features and changes that have already been merged to the main branch and are awaiting release in this version.
 
-**Note:** DataFusion `50.0.0` has not been released yet. The information provided in this section pertains to features and changes that have already been merged to the main branch and are awaiting release in this version.
-You can see the current [status of the `50.0.0 `release here](https://github.com/apache/datafusion/issues/16799)
+You can see the current [status of the `51.0.0 `release here](https://github.com/apache/datafusion/issues/17558)
+
+## DataFusion `50.0.0`
 
 ### ListingTable automatically detects Hive Partitioned tables