Flowcharting
I believe there is no separate flowcharting manual.
as the manuals say:
When using the flowchart method of programming, only a small subset of the available
commands are supported by the on-screen simulation. These commands are indicated by the corresponding flowchart icon by the description.
Some words are provided in Manual 1 page 53 . . .
In manual 2, for commands which can be used in flowcharting, there is a flowchart symbol in the top right corner of the command details page. For example see page 42, 55, 56, 66, . . . etc
Depending upon how keen you are to get your child into flowcharting,
Rev Ed also have as shareware:
Logicator for PIC® and PICAXE® micros (version 3)
goto
http://www.rev-ed.co.uk/picaxe/ and click in the software tab.
and look at
http://www.rev-ed.co.uk/docs/cat_07.pdf
Be warned that most here program in BASIC and help for flowcharting questions may be therefore limited.