Update the mod_ssl and mod_php sections of the handbook.
A fine addition to the chapter, well structured.
I've added a few comments and a suggestion inline.
Is it "train of trust" or "chain of trust"?
There seems to be a word missing between "users" and "prevent".
You could have kept the <application>Apache</application> part here.
How about simply "to activate it"?
Minor thing remaining, the rest looks good.
One more thing I noticed just now that I reread it: we discourage the use of "you".