doc: update release instructions

Author: David Miguel Susano Pinto

doc/get-involved/maintaining.rst

@@ -38,8 +38,8 @@ there should be no need to check it.
    with tags such as ``snapshot-N``::
 
     VERSION=$(python3 setup.py --version)
-    sed -i "s,(upcoming),($(date +%Y/%m/%d))," NEWS
-    git commit -m "maint: release $VERSION" setup.py NEWS
+    sed -i "s,(upcoming),($(date +%Y/%m/%d))," NEWS.rst
+    git commit -m "maint: release $VERSION" setup.py NEWS.rst
     COMMIT=$(git rev-parse HEAD | cut -c1-12)
     git tag -s -u $GPGKEY \
       -m "Added tag release-$VERSION for commit $COMMIT" release-$VERSION