[css-align] Another place where self-start makes no sense, because it's not a content alignment value.

Author: tabatkins

css-align/Overview.bs

@@ -300,7 +300,7 @@ Baseline Alignment: the ''baseline'' and ''last-baseline'' keywords</h3>
 
 	When specified for 'align-content'/'justify-content',
 	these values trigger <a>baseline content-alignment</a>,
-	shifting the content of the box within the box,
+	shifting the content of the box within its content box,
 	and may also affect the sizing of the box itself.
 	See [[#baseline-align-content]].
 
@@ -312,7 +312,7 @@ Baseline Alignment: the ''baseline'' and ''last-baseline'' keywords</h3>
 
 	If both <a>baseline content-alignment</a> <em>and</em> <a>baseline self-alignment</a> are specified in the same axis on the same box,
 	only <a>baseline self-alignment</a> is honored in that axis;
-	the content-alignment in that axis must be treated as ''self-start''.
+	the content-alignment in that axis must be treated as ''start''.
 
 	Issue: The previous paragraph is fairly arbitrary.
 	Need some experience to make sure it's the correct choice out of the two possibilities.