Make the Declaration Order recommendation optional

This recommendation was relaxed in the internal style guide a few months ago. The suggestion is still to continue using alphabetical order unless teams have access to the appropriate tooling which can support consistently automating and enforcing different sorting rules which may be more logical to read.

htmlcssguide.html

@@ -735,10 +735,12 @@ <h3 id="CSS_Formatting_Rules" class="numbered">CSS Formatting Rules</h3>
 
 <h4 id="Declaration_Order" class="numbered">Declaration Order</h4>
 
-<p>Alphabetize declarations.</p>
+<p>Alphabetize declarations (optional).</p>
 
-<p>Put declarations in alphabetical order in order to
-achieve consistent code in a way that is easy to remember and maintain.</p>
+<p>Sort declarations consistently within a project. In the absence of tooling to
+automate and enforce a consistent sort order, consider putting declarations in
+alphabetical order in order to achieve consistent code in a way that is easy to
+learn, remember, and manually maintain.</p>
 
 <p>Ignore vendor-specific prefixes for sorting purposes. However, multiple
 vendor-specific prefixes for a certain CSS property should be kept sorted (e.g.