fix missing img directory in src

Author: svgeesus

css-text-decor-4/Overview.bs

@@ -3,6 +3,8 @@ Title: CSS Text Decoration Module Level 4
 Shortname: css-text-decor
 Level: 4
 Status: FPWD
+Date: 2018-03-13
+Prepare for TR: true
 Work Status: Exploring
 Group: csswg
 ED: https://drafts.csswg.org/css-text-decor-4/
@@ -145,7 +147,7 @@ Determining the Position and Thickness of Line Decorations</h3>
 								 are rendered in a small font. In the second rendering,
 								 the 'a' is rendered in a larger font. In the third, both
 								 '1st' and 'a' are large."
-						height="105" src="underline-averaging.gif" width="326">
+						height="105" src="img/underline-averaging.gif" width="326">
 		<p>In the three fragments of underlined text, the underline is drawn
 			consecutively lower and thicker as the ratio of large text to small
 			text increases.</p>
@@ -292,7 +294,7 @@ Text Decoration Line Continuity: the 'text-decoration-skip' property</h4>
 			<div class="figure">
 				<p><img title="text-decoration-skip: edges"
 						alt="An underline below a series of Chinese characters has a gap between two adjacent underlining elements."
-						src="decoration-skip-edges.png"
+						src="img/decoration-skip-edges.png"
 						>
 				<p class="caption">''text-decoration-skip: edges'' for <code>&lt;u>石井&lt;/u>&lt;u>艾俐俐&lt;/u></code>
 </p>