[comment addon] Adjust docs for padding

Closes #2391
Closes #2387

Author: marijnh

doc/manual.html

@@ -2165,8 +2165,9 @@ <h2>Addons</h2>
         <dd>Override the <a href="#mode_comment">comment string
         properties</a> of the mode with custom comment strings.</dd>
         <dt><code><strong>padding</strong>: string</code></dt>
-        <dd>A string that will be inserted after opening and before
-        closing comment markers. Defaults to a single space.</dd>
+        <dd>A string that will be inserted after opening and leading
+        markers, and before closing comment markers. Defaults to a
+        single space.</dd>
         <dt><code><strong>commentBlankLines</strong>: boolean</code></dt>
         <dd>Whether, when adding line comments, to also comment lines
         that contain only whitespace.</dd>