fixup! Bug 41916: Letterboxing preferences UI

Bug 42665: Drop the "tail-with-learn-more" class from our descriptions.

browser/components/preferences/letterboxing.inc.xhtml

@@ -7,10 +7,7 @@
 >
   <html:h1 data-l10n-id="letterboxing-header" />
   <description class="letterboxing-overview description-deemphasized">
-    <html:span
-      data-l10n-id="letterboxing-overview"
-      class="tail-with-learn-more"
-    ></html:span>
+    <html:span data-l10n-id="letterboxing-overview"></html:span>
     <html:a
       is="moz-support-link"
       tor-manual-page="anti-fingerprinting_letterboxing"
@@ -26,10 +23,7 @@
   <label><html:h2
     data-l10n-id="letterboxing-window-size-header"/></label>
   <description class="letterboxing-search-overview description-deemphasized">
-    <html:span
-      data-l10n-id="letterboxing-overview"
-      class="tail-with-learn-more"
-    ></html:span>
+    <html:span data-l10n-id="letterboxing-overview"></html:span>
     <html:a
       is="moz-support-link"
       tor-manual-page="anti-fingerprinting_letterboxing"
@@ -51,10 +45,7 @@
     data-l10n-id="letterboxing-alignment-header"
     /></label>
   <description class="letterboxing-search-overview description-deemphasized">
-    <html:span
-      data-l10n-id="letterboxing-overview"
-      class="tail-with-learn-more"
-    ></html:span>
+    <html:span data-l10n-id="letterboxing-overview"></html:span>
     <html:a
       is="moz-support-link"
       tor-manual-page="anti-fingerprinting_letterboxing"
@@ -100,10 +91,7 @@
   <label class="letterboxing-search-heading"><html:h2
     data-l10n-id="letterboxing-header"/></label>
   <description class="letterboxing-search-overview description-deemphasized">
-    <html:span
-      data-l10n-id="letterboxing-overview"
-      class="tail-with-learn-more"
-    ></html:span>
+    <html:span data-l10n-id="letterboxing-overview"></html:span>
     <html:a
       is="moz-support-link"
       tor-manual-page="anti-fingerprinting_letterboxing"