docs: Fix some formatting oddities

When describing attributes and elements, we mostly stick to
a certain pattern; however, there are a few cases when the
information is not presented in the usual way.

Since there doesn't seem to be any reason not to follow the
tried and true formula, rework those bits to fit the rest of
the documentation.

docs/formatnetwork.html.in

@@ -54,13 +54,14 @@
         The format must be RFC 4122 compliant, eg <code>3e3fce45-4f53-4fa7-bb32-11f34168b82b</code>.
         If omitted when defining/creating a new network, a random
         UUID is generated. <span class="since">Since 0.3.0</span></dd>
-      <dt><code>ipv6='yes'</code></dt>
-      <dd>The new, optional parameter <code>ipv6='yes'</code> enables
+      <dt><code>ipv6</code></dt>
+      <dd>When set to <code>yes</code>, the optional parameter
+        <code>ipv6</code> enables
         a network definition with no IPv6 gateway addresses specified
         to have guest-to-guest communications.  For further information,
         see the example below for the example with no gateway addresses.
         <span class="since">Since 1.0.1</span></dd>
-      <dt><code>trustGuestRxFilters='yes'</code></dt>
+      <dt><code>trustGuestRxFilters</code></dt>
       <dd>The optional parameter <code>trustGuestRxFilters</code> can
         be used to set that attribute of the same name for each domain
         interface connected to this network (<span class="since">since