[css-align] Fixed headings.

Author: tabatkins

css-align/Overview.bs

@@ -184,7 +184,7 @@ Alignment Values</h2>
 	</dl>
 
 <h3 id='positional-values'>
-Positional Alignment: the ''center'', ''stretch'', ''start'', ''end'', ''self-start'', ''self-end'', ''flex-start'', ''flex-end'', ''left'', and ''right'' keywords</h3>
+Positional Alignment: the ''center'', ''start'', ''end'', ''self-start'', ''self-end'', ''flex-start'', ''flex-end'', ''left'', and ''right'' keywords</h3>
 
 	The positional alignment keywords specify a position for an <a>alignment subject</a>
 	with respect to its <a>alignment container</a>.
@@ -351,7 +351,7 @@ Baseline Alignment: the ''baseline'' and ''last-baseline'' keywords</h3>
 
 
 <h3 id='distribution-values'>
-Distributed Alignment: the ''space-between'', ''space-around'', and ''space-evenly'' keywords</h3>
+Distributed Alignment: the ''center'', ''space-between'', ''space-around'', and ''space-evenly'' keywords</h3>
 
 	The distribution values are used by 'justify-content' and 'align-content'
 	to distribute the items in the <a>alignment subject</a>