annotate docs/README @ 4327:9521698a9894

exthelper: support the option argument when registering a command

Largefiles uses this 5th argument with push and pull, so this will be tested in
the next commit.  I assume the reason for unrolling and reforming the tuple in
each finalxxxsetup() is to validate that something proper was passed in when
registering.  But it's better to explode when decorating than during the delayed
actual registration.

Doc is generated with sphinx.

You can generate the doc with:

```
make
```

# Tutorials

For updating the tutorials, you need to have the docgraph extension installed
(https://pypi.python.org/pypi/hg-docgraph).

Then run the test-topic-tutorial.t and test-tutorial.t to update the output if
needed.

You'll need the dot binary (likely installed by the graphviz package in your
package manager) in order to have graphviz graphs rendered in the html output.

Simply run make in the docs directory should takes care of the conversion of
the tutorial .t files into .rst files. Then sphinx should do the rest of the
jobs by rendering graphviz graphs.