PHP samples fixes

Yeah - this is one of the shortcomings of the placeholder convention, right now: it obscures native types. @jamiehannaford's way is right. I do wish we could inject markup and style placeholders differently to make them stand out more, because this looks even weirder than they usually do.

Another option is to assign a `$loadBalancer` in a prior example and extract its `id` programmatically here. I like to do that when I can because

 * it ties the examples together into a more cohesive narrative;
 * it clarifies where you can actually get the ID; and
 * it keeps the sample syntax valid.