Update README for the installation of kibana and kql packages

[pberba]

Pull Request

Issue link(s):

Summary - What I changed

Updated Getting started section to the correct way to install the kibana and kql packages from the repository. Using the following

pip3 install git+https://github.com/elastic/detection-rules.git#subdirectory=kibana
pip3 install git+https://github.com/elastic/detection-rules.git#subdirectory=kql

Results in this error

ERROR: git+https://github.com/elastic/detection-rules.git#subdirectory=kibana does not appear to be a Python project: neither 'setup.py' nor 'pyproject.toml' found.

How To Test

Checklist

• Added a label for the type of pr: bug, enhancement, schema, maintenance, Rule: New, Rule: Deprecation, Rule: Tuning, Hunt: New, or Hunt: Tuning so guidelines can be generated
• Added the meta:rapid-merge label if planning to merge within 24 hours
• Secret and sensitive material has been managed correctly
• Automated testing was updated or added to match the most common scenarios
• Documentation and comments were added for features that require explanation

Contributor checklist

• Have you signed the contributor license agreement?
• Have you followed the contributor guidelines?

[cla-checker-service]

❌ Author of the following commits did not sign a Contributor Agreement:
584d914, f34246b

Please, read and sign the above mentioned agreement if you want to contribute to this project

[Mikaayenson]

👋 Thanks for the submission @pberba . Once you sign the CLA, this should be g2g.