update_checkout.py: fix inconsistent options help capitalization (#68374)

`--clone` and `--clone-with-ssh` help strings were using capitalization inconsistent with other options.

Author: MaxDesiatov

utils/update_checkout/update_checkout/update_checkout.py

@@ -567,11 +567,11 @@ def main():
 """)
     parser.add_argument(
         "--clone",
-        help="Obtain Sources for Swift and Related Projects",
+        help="obtain sources for Swift and related projects",
         action="store_true")
     parser.add_argument(
         "--clone-with-ssh",
-        help="Obtain Sources for Swift and Related Projects via SSH",
+        help="Obtain sources for Swift and related projects via SSH",
         action="store_true")
     parser.add_argument(
         "--skip-history",