[css-flexbox-1] Fix punctuation, add possessive, and tag issue.

Author: fantasai

css-flexbox-1/Overview.bs

@@ -741,14 +741,14 @@ Absolutely-Positioned Flex Children</h3>
 
 	The [=cross-axis=] edges of the [=static-position rectangle=]
 	of an absolutely-positioned child of a <a>flex container</a>
-	are the [=content edges=] of the [=flex container=]
+	are the [=content edges=] of the [=flex container=].
 	The [=main-axis=] edges of the [=static-position rectangle=]
 	are where the [=margin edges=] of the child would be positioned
 	if it were the sole <a>flex item</a> in the <a>flex container</a>,
 	assuming both the child and the flex container
 	were fixed-size boxes of their used size.
 	(For this purpose,
-	''margin/auto'' margins are treated as zero.)
+	the child's 'margin/auto'' margins are treated as zero.)
 
 	<wpt>
 		abspos/abspos-autopos-htb-ltr.html
@@ -3723,7 +3723,8 @@ Changes since the <a href="https://www.w3.org/TR/2018/CR-css-flexbox-1-20181119/
 			rather than doing extra layout work.
 			This will result in ignoring 'align-content' on the flex container,
 			but allow 'align-self' on the box itself to still take effect.
-			(<a href="https://github.com/w3c/csswg-drafts/issues/5843">Issue 5843</a>)
+			(<a href="https://github.com/w3c/csswg-drafts/issues/5843">Issue 5843</a>,
+			<a href="https://github.com/w3c/csswg-drafts/issues/7596">7596</a>)
 
 		<li id="change-2018-correctly-ignore-auto">
 			Correctly ignore ''width/auto'' [=preferred sizes=]