Doc(eos_designs): Update documentation to customize WAN flow tracking.

[gmuloc]

Change Summary

The documentation is a bit outdated (though correct) as it is not mentioning the recently introduced keys

Component(s) name

arista.avd.eos_designs

Proposed changes

• Add reference to the fabric_flow_tracking and flow_tracking_settings keys
• Add an example on how to configure flow-tracking on a per WAN interface basis
• Fix a schema description not mentioning the network-services l3_interfaces

How to test

only doc

Checklist

Repository Checklist

• My code has been rebased from devel before I start
• I have read the CONTRIBUTING document.
• My change requires a change to the documentation and documentation have been updated accordingly.
• I have updated molecule CI testing accordingly. (check the box if not applicable)

[github-actions]

Review docs on Read the Docs

To test this pull request:

# Create virtual environment for this testing below the current directory
python -m venv test-avd-pr-4253
# Activate the virtual environment
source test-avd-pr-4253/bin/activate
# Install all requirements including PyAVD
pip install "pyavd[ansible] @ git+https://github.com/gmuloc/avd.git@fix-doc-flow-tracking#subdirectory=python-avd" --force
# Install Ansible collection
ansible-galaxy collection install git+https://github.com/gmuloc/avd.git#/ansible_collections/arista/avd/,fix-doc-flow-tracking --force
# Optional: Install AVD examples
cd test-avd-pr-4253
ansible-playbook arista.avd.install_examples

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud