Add missing margin for headers (#1494)

3rd level headers (are not properly aligned) with the text.
The change adds missing left margin.

Author: stefanchrobot

assets/less/content/general.less

@@ -161,7 +161,12 @@ td, th {
   }
 }
 
-.detail h2.section-heading {
+.detail h1.section-heading,
+.detail h2.section-heading,
+.detail h3.section-heading,
+.detail h4.section-heading,
+.detail h5.section-heading,
+.detail h6.section-heading {
   margin-left: 0.3em;
 }