Add notice for modern Node.js versions

[jonkoops]

Adds a notice to the README that explains to the user they might not need this module with example code that could replace the module in their project if they are targeting newer versions of Node.js.

See #29 for related discusssion.

[bjohansebas]

In npm, it doesn't follow the same format, and the styles that GitHub applies to this type of notes wouldn't be applied

[jonkoops]

Bummer, but would that be a reason to hold it up? I believe NPM will just show this as quoted text, which seems a reasonable fallback.

[UlisesGascon]

Let's see if we can clarify this in the npm channel: https://openjs-foundation.slack.com/archives/CTEDKHCTB/p1729968334939499 🤔

[bjohansebas]

The view on npm would look something like this

[blakeembrey]

Doesn’t it basically say this above already? Why not reword the exist text saying what the package is for? Existing text:

This module provides an export that is just like http.METHODS from Node.js core,
with the following differences
[…] * Contains a fallback list of methods for Node.js versions that do not have a http.METHODS export (0.10 and lower).

Can we try to merge the redundancy in this description? Maybe link to the node docs instead of the code sample since you can write it at least 4 different ways nowadays depending on CommonJS, ESM, non-node prefixes?

[UlisesGascon]

+1 to Blake's proposal

[jonkoops]

I've revised the notice not to repeat aforementioned statements and simply instruct the user to use the core module if their support target allows, sans code example.

[coveralls]

coverage: 100.0%. remained the same
when pulling 6f3ed49 on jonkoops:redundant-notice
into e5f5400 on jshttp:master.