[css-ui] Remove more extraneous quotes

Author: frivoal

css-ui/Overview.bs

@@ -657,7 +657,7 @@ that has 'overflow'
 other than ''visible''.
 
 Text can overflow for example when it is prevented from wrapping
-(e.g. due to '<code class="lang-css">white-space: nowrap</code>'
+(e.g. due to <code class="lang-css">white-space: nowrap</code>
 or a single word is too long to fit).
 Values have the following meanings:
 

css-ui/Overview.html

@@ -2258,7 +2258,7 @@ <h3 class="heading settled" data-level="5.2" id="text-overflow"><span class="sec
 
 
    <p>Text can overflow for example when it is prevented from wrapping
-(e.g. due to '<code class="lang-css">white-space: nowrap</code>'
+(e.g. due to <code class="lang-css">white-space: nowrap</code>
 or a single word is too long to fit).
 Values have the following meanings:</p>