consider supporting .node-version spec

[ScottChapman]

Please see https://github.com/shadowspawn/node-version-usage

This would allow projects to be more node version manager agnostic

[ljharb]

The reasons why it's prohibitive for nvm to support this are discussed here.

[shadowspawn]

See also: #794 and #1625

Supporting a simple static version does not seem prohibitive?
#794 (comment)

(To be clear relative to the title of this issue, there is not a spec for .node-version. There are some existing implementations. 🙂 )

[ljharb]

Ah yes, thank you. Duplicate of #794, in particular.

(Supporting a single static version is fine if that's all other tools support too. A common filename with tools inconsistently supporting formats in it is a recipe for disaster)