[css-text-3][editorial] Gloss "out-of-flow" jargon (#13066)

Approx. backport of #13030

Author: cvrebert

css-text-3/Overview.bs

@@ -848,7 +848,7 @@ Mapping Rules</h4>
 	For ''capitalize'', what constitutes a “word“ is UA-dependent;
 	[[!UAX29]] is suggested (but not required)
 	for determining such word boundaries.
-	Out-of-flow elements and inline element boundaries
+	[=Out-of-flow=] elements and inline element boundaries
 	must not introduce a 'text-transform' word boundary
 	and must be ignored when determining such word boundaries.
 
@@ -3431,7 +3431,7 @@ Line Breaking Details</h3>
 			and is forbidden under ''line-break: anywhere''.
 
 		<li>
-			Out-of-flow elements
+			[=Out-of-flow=] elements
 			and inline element boundaries
 			do not introduce a [=forced line break=]
 			or [=soft wrap opportunity=] in the flow.
@@ -4763,7 +4763,7 @@ Hyphenation: the 'hyphens' property</h3>
 	For the purpose of the 'hyphens' property,
 	what constitutes a “word” is UA-dependent.
 	However, inline element boundaries
-	and out-of-flow elements
+	and [=out-of-flow=] elements
 	must be ignored when determining word boundaries.
 
 	<wpt>