[css-grid-1] Add reminder note about fit-content/auto being treated like max-content to the section where it matters the most.

Author: fantasai

css-grid-1/Overview.bs

@@ -3989,6 +3989,10 @@ Resolve Intrinsic Track Sizes</h3>
 	all intrinsic <a>base sizes</a> and <a>growth limits</a>
 	will have been resolved to absolute lengths.
 
+	Note: [[#algo-terms|Remember that]] ''fit-content()'' and ''auto'' [=max track sizing functions=]
+	are treated the same as ''max-content''
+	except where explicitly specified otherwise.
+
 <!--
 	When the <a>grid container</a> is being sized under a <a>min-content constraint</a>,
 	a track with a flexible <a>min track sizing function</a>