Updating README file on installation for new qibotn users

[NithyasriVS]

To help new users of qibotn to install qibotn in the right manner since qibotn no longer uses pip install . for installation after the release. Changing the directions for installation in the readme file to the following

git clone https://github.com/qiboteam/qibotn.git
cd qibotn
poetry install

[alecandido]

Notice that using Poetry is only relevant to use it for development. Otherwise, pip install . is still working as usual (and even pip install -e ., which is good enough for development as well, if you're not keen on Poetry).

[NithyasriVS]

Hi thanks @alecandido, thank you! Just wanted to put it out there because I faced the issue. Thanks a lot for sharing the work around of using pip install -e for dev purposes instead of poetry.

[alecandido]

You're welcome :)

And I'm not opposing the change in the README (though I start wondering if we should keep this kind of information in the README in general).
However, notice that pip install -e . is not necessarily a workaround, but a product of the integration and standardization happening in Python building infrastructure (you can read more about that in the original specification).

I.e. by calling pip install -e . you're essentially invoking the poetry-core build backend (the one provided by Poetry). The part you would miss wrt poetry install will be the environment management, for which we provide additional specifications, in particular if you want to work with tests or docs. But other than that, you can manage the environment on your own (even using tools like virtualenv, Conda, or other ones), and you will be responsible for the development dependencies (like Pytest to run the tests or Sphinx to generate the docs), but the package will be provided in the very same way (and the -e adds the editable installation, you can read more about that in its specification).

[NithyasriVS]

@alecandido Right, I understand. If at all it's indeed information that we want to keep on the README file, it could probably be under a heading called "How to Contribute" instead of "Installation" then because this only for development purposes. But it any case, this information is found in the documentation of qibotn.

Thank you for your insights on pip install -e. That was good to learn!

[scarrazza]

@NithyasriVS, @Vinitha-balachandran we are planning to make a new release later this week. May I ask you to create a new section in the README and move these changes there? For the general user, the installation instruction should be pip install qibotn for the latest stable release.

[NithyasriVS]

@NithyasriVS, @Vinitha-balachandran we are planning to make a new release later this week. May I ask you to create a new section in the README and move these changes there? For the general user, the installation instruction should be pip install qibotn for the latest stable release.

Hi @Vinitha-balachandran , @scarrazza, I have changed it to pip install qibotn and also included the change suggested in this PR (Installation for dev/contribution purpose through poetry). Thank you.

[scarrazza]

Thanks.