Document default MC image for MinIOJob CRD

[pjuarezd]

• Document default MC image in the adocs
• Add release script section to set a defined mc image instead of 'latest'

When we create the release PR, the default latest mc image tag will be replaced by the date format of the latest mc relaesed image

RELEASE=v6.0.0 make release

[ramondeklein]

LGTM. I like that we now have a fixed version. Makes it more predictable.

[pjuarezd]

Failing test is because of govulncheck found https://pkg.go.dev/vuln/GO-2024-2527

1. There is no fix yet for this package
2. govulncheck do not support to silence or ignore a vulnerability, per the docs on limitations

There is no support for silencing vulnerability findings. See https://go.dev/issue/61211 for updates.

Evaluationg if we should we disable the govulncheck github action? or just ignore the error and merge for the forsee times until the vuln is fixed.
cc @harshavardhana @dvaldivia