Remove specification of one year curation requirement for contributions

[phyy-nx]

As discussed in the Nov 2025 Telco, nowadays the one-year requirement for contributed definitions to incubate seems too long given the pace of development. This PR drops the requirement, but notably, I couldn't find the explicit requirement anywhere, including our constitution, except this applying-nexus.rst page!

[benajamin]

I don't think you'll find it written anywhere, except maybe in the minutes of a very early NIAC meeting. I remember discussion of the policy's aim was for people to "eat their own dog food" for a while to make sure that the proposed definition did fulfill the requirements of the proposers. I think that now we have a much better understanding of the general requirements and a broad range of examples to compare to, such that the 1-year policy can be relaxed, or perhaps removed altogether.

[paulmillar]

One place from which we might draw inspiration is IETF. I believe their standards track requires multiple (as in "more than one") server- and client implementations, with demonstrable interoperability between all (server,client) implementation pairs.

I think we could translate this into NeXus by requiring a proposed AP to be included in data from multiple facilities and multiple software packages that can understand the AP. We would demonstrate interoperability by showing each software package can consume data from any of the facility's beamlines (that supports the proposed AP) before accepting the AP as standard.

That said, I'm not sure how practical this would be.