[css-align-3] Fallback alignment for 'last baseline' is 'safe end' per WG resolution. Fixes #1611.

Author: fantasai

css-align-3/Overview.bs

@@ -607,7 +607,7 @@ Baseline Alignment: the ''baseline'' keyword and ''first''/''last'' modifiers</h
 			of its [=baseline-sharing group=].̣
 			See [[#align-by-baseline]] for more details.
 
-			The <a>fallback alignment</a> for ''last baseline'' is ''end''.
+			The <a>fallback alignment</a> for ''last baseline'' is ''safe end''.
 	</dl>
 
 	When specified for 'align-content',