MINOR: [R] Update NEWS for 21.0.0.1 Release (#47324)

### Rationale for this change

Update NEWS for 21.0.0.1 release

### What changes are included in this PR?

Update NEWS for 21.0.0.1 release

### Are these changes tested?

No

### Are there any user-facing changes?

No

Lead-authored-by: Nic Crane <[email protected]>
Co-authored-by: Jonathan Keane <[email protected]>
Signed-off-by: Nic Crane <[email protected]>

Author: thisisnic

r/NEWS.md

@@ -17,6 +17,14 @@
   under the License.
 -->
 
+# arrow 21.0.0.9000
+
+# arrow 21.0.0.1
+
+##  Minor improvements and fixes
+
+- Patch bundled version of Thrift to prevent CRAN check failures (@kou, #47286)
+
 # arrow 21.0.0
 
 ## New features