Quite well done, very descriptive and good job in not overusing screenshots.
I would personally suggest a different structure to your documents though.
But, with great criticism must come great suggestions as well. At least, that’s what I think. ^_^
When explaining steps, try a list.
Example (your first paragraph about the parser):
When a page request loads the front-end index.php file, it passes to the server the ID or the alias of the document being requested. The index.php file initializes the modx object and starts the parser. The parser first determines if this is a document ID or an alias. If it’s the alias, it finds the document’s ID. Then it gets the site’s configuration from the database. If the site is configured to be offline, either the document specified to be the “offline” document or a plain default document with a simple message is displayed (this behavior is specified in the main Configuration form).
I would describe this paragraph as:
Steps of the MODx parser:
- Client requests a file (by ID or alias)
- Index.php sends the request (by ID or alias) to the Parser.
- If the request is an alias, retrieve the ID from the database
- Retrieve the Site Configuration from the database
- If the site is configured to be offline, retrieve the "offline" document (this is specified in the configuration)
Plain explenations are a bitch to wade through for people just looking for a quick overview. Of course this is just a quick mock-up, but you get the idea.
Ps. Yes, I wrote several help-files. And there’s some larger posts from me in the snippets forum as well, like a PDF generator.