Show deprecation reason in stdlib docs on rescript-lang.org

[yangdanny97]

For example: https://rescript-lang.org/docs/manual/api/stdlib/option/#value-getWithDefault just shows a "deprecated" banner, but it doesn't show what API should be used instead.

Reading the code & in the sandbox I can see the reason:

Use getOr instead

It would be nice to also have that on the documentation website

[aspeddro]

Related rescript-lang/rescript#8396

When we push a tag on master the docs will be updated with reason message

[aspeddro]

@jderochervlk the file stdlib.json has updated in https://github.com/rescript-lang/rescript-lang.org/blob/master/data/api/v12.3.0

The latest version is 12.3.0. The website dont show the deprecated message. The code read the json file from markdown-pages/docs/api/${moduleName}.json

rescript-lang.org/apps/docs/app/routes/ApiDocs.res

Lines 354 to 355 in 02f7b35

	let moduleContent =
	Fs.readFileSync(`markdown-pages/docs/api/${moduleName}.json`)->JSON.parseOrThrow

rescript-lang.org/data/api/v12.3.0/stdlib.json

Line 6916 in 02f7b35

"deprecated": "Use getOr instead"