In the context that you outline, it seems quite natural for a speaker to use the we pronoun, because, as @Brandin notes, such jobs are normally done in teams. And anyway, it's part of an online forum, so the person's likely intent is to say "How does one configure a webserver to serve PHP content?" (similar to how on in French stands for both 'one' and 'we').
There's another explanation, though, and that does involve the royal we. As Wikipedia notes,
In Hindustani and other Indo-Aryan languages, the majestic plural is a common way for elder speakers to refer to themselves, and also for persons of higher social rank to refer to themselves. In certain communities, the first-person singular (Hindi: मैं, romanized: main, lit. 'I') may be dispensed with altogether for self-reference and the plural nosism [is] used uniformly.
I can confirm this- as a speaker of Hindi, this happens often and is not at all uncommon. Here's an example:
When I add two to two, I get four.
This even sounds a bit off in English! No, what we'd use is:
When we add two to two, we get four.
When one adds two to two, one gets four.
(Okay, that last one's also kinda weird) But the same is true in Hindi: a Hindi speaker would say 'Jab hum do ko do se milate hain, hume char milta he.' This is extended to nearly any situation in which the solution or outcome is applicable to everyone. Presumably, the answer to the original question (how you set up the webserver) is a solution that anyone can go and use.
Most of the time, though, it's just a phenomenon people naturally carry over from their native languages- in this case, Hindi (?) speakers doing in English what's natural for them to do in Hindi.