Adjust guidelines for vrf_vni values

[ClausHolbechArista]

Change Summary

We don't enforce the vrf_vni : < 1-1024 > limit documented in the Readme file, so this change is only for adjusting the guidelines in Readme.md to make the user aware of what to look out for, before using vrf_vni > 1024.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Documentation content changes
• Other (please describe):

Related Issue(s)

Fixes #314

Component(s) name

eos_l3ls_evpn

Proposed changes

• Readme updated with following guidelines:

        # VRF VNI | Required.
        # The VRF VNI range is not limited, but it is recommended to keep vrf_vni <= 1024
        # It is necessary to keep [ vrf_vni + MLAG IBGP base_vlan ] < 4094 to support MLAG IBGP peering in VRF.
        # If vrf_vni > 1094 make sure to change mlag_ibgp_peering_vrfs: { base_vlan : < > } to a lower value (default 3000).
        # If vrf_vni > 10000 make sure to adjust mac_vrf_vni_base accordingly to avoid overlap.
        vrf_vni: < 1-1024 >

• Small formatting changes for vrf_vni

Types of changes

How to test

Before changing anything I tested with vrf_vni > 1024 and it worked fine. The MLAG IBGP VLANs are calculated as vrf_vni + base_vlan so I ended up with VLAN numbers > 4096. Hence we need guidelines to make the user aware.

Checklist:

• I have read the CONTRIBUTING document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• All new and existing tests passed (pre-commit, make linting and make sanity-lint).
• I have updated molecule CI testing accordingly

[ClausHolbechArista]

LGTM :)