README on main points to non-existing v2 branch

[hash-d]

The v2 branch was renamed to main, but the README still points to v2:

(...)
- name: Creating Skupper resources on west namespace
  skupper.v2.resource:
    path: "{{ item }}"
    namespace: "west"
  with_items:
    - https://raw.githubusercontent.com/skupperproject/skupper-example-yaml/refs/heads/v2/west/frontend.yaml
    - https://raw.githubusercontent.com/skupperproject/skupper-example-yaml/refs/heads/v2/west/site.yaml
(...)

[hash-d]

This is a duplicate of #93