Fix 19.rst file

Author: JMazurkiewicz

libcxx/docs/ReleaseNotes/19.rst

@@ -78,7 +78,7 @@ Implemented Papers
 - P1981R0 - Rename ``leap`` to ``leap_second``
 - P1982R0 - Rename ``link`` to ``time_zone_link``
 - P2602R2 - Poison Pills are Too Toxic (as DR against C++20)
-- 
+
 
 Improvements and New Features
 -----------------------------