[css-flexbox-1] Cross-link to term 'automatic size'.

Author: fantasai

css-flexbox-1/Overview.bs

@@ -1736,9 +1736,9 @@ The 'flex' Shorthand</h3>
 
 				<dt><dfn>content</dfn>
 				<dd>
-					Indicates an <a href="#algo-main-item">automatic size</a>
+					Indicates an [=automatic size=]
 					based on the <a>flex item</a>’s content.
-					(It is typically equivalent to the <a>max-content size</a>,
+					(This is typically equivalent to the <a>max-content size</a>,
 					but with adjustments to handle [=preferred aspect ratios=],
 					intrinsic sizing constraints,
 					and orthogonal flows;