Command to update submodules

[quaternic]

(This is really quite a minor issue, but became problematic due to the unfortunate combination of me reading the Using Git -chapter as a stand-alone guide, wanting to get git to a clean working tree asap, and being prone to thinking "this doesn't work so I must figure out why".)

The note about submodules claims that running ./x --help would automatically update the submodules, but it does not.

After digging into bootstrap's implementation, I found out that you'd have to either give some command that actually does something (setup is specifically excluded), or request verbose help for a valid command.

These update submodules:

./x setup --help --verbose
./x clean --help --verbose
./x clean

(The last one has side effects: it starts to download nightly for whatever reason)

These don't update submodules:

./x
./x --help
./x setup
./x setup --help
./x clean -h
./x foobar --help --verbose

The further I get with writing this, the more it seems like a bug in the implementation, but it would be much easier to fix the guide to say that ./x setup -h -v is one way to do that without doing much else.

[tshepang]

we could change that to git submodule update, instead of relying on side effects that may change in future