doc: Improve Makefile (#387)

* Add help target to the Makefile

It is often expected to have a `help` target in a Makefile. This one is
automatically generated from comments in the Makefile so it is easier to
maintain.

This commit only documents targets that seem the most important.

* Add the server address and port on `make serve`

Developers should not have to read the documentation to find where to
point their browsers to access ihatemoney application.

* Add .PHONY instructions to the Makefile

`.PHONY` instructs Make to not look, for instance, for an `install` file
before executing the corresponding target. If such a file would exist,
the command would not be performed at all. This is because Make is
initially intended to create files (i.e. targets) and consider there is
nothing to do if the file already exists.

More information on https://stackoverflow.com/a/2145605.

0 files changed, 0 insertions, 0 deletions