Use less intrusive style for displaying unit flags

Those usually are not main priority for translators, so the goal is to
focus more on comments and file location hints. Legend seems like a nice
fit with smaller text and gray color instead of black, but of course it
slightly kills semantics.

weblate/html/translate.html

@@ -139,7 +139,7 @@
 {% if unit.flags %}
 <tr>
 <th>{% trans "Flags" %}</th>
-<td>{{ unit.flags }}</td>
+<td><span class="legend">{{ unit.flags }}</span></td>
 </tr>
 {% endif %}
 <tr><td></td><td>