doc: deprecate coercion to integer in process.exit

This warns of invalid uses of process.exit([code]) and recommends the
correct practice.

Signed-off-by: Daeyeon Jeong daeyeon.dev@gmail.com

doc/api/deprecations.md

@@ -3145,6 +3145,20 @@ parameter in [`fs.write()`][], [`fs.writeFile()`][], [`fs.appendFile()`][],
 [`fs.writeFileSync()`][], and [`fs.appendFileSync()`][] is deprecated.
 Convert them to primitive strings.
 
+### DEP0163: `process.exit([code])` coercion to integer
+
+<!-- YAML
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/43738
+    description: Documentation-only deprecation.
+-->
+
+Type: Documentation-only
+
+Implicit coercion of a non-integer `code` parameter in [`process.exit()`][] is
+deprecated. Please use an integer value.
+
 [Legacy URL API]: url.md#legacy-url-api
 [NIST SP 800-38D]: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf
 [RFC 6066]: https://tools.ietf.org/html/rfc6066#section-3
@@ -3221,6 +3235,7 @@ Convert them to primitive strings.
 [`os.networkInterfaces()`]: os.md#osnetworkinterfaces
 [`os.tmpdir()`]: os.md#ostmpdir
 [`process.env`]: process.md#processenv
+[`process.exit()`]: process.md#processexitcode
 [`process.getActiveResourcesInfo()`]: process.md#processgetactiveresourcesinfo
 [`process.mainModule`]: process.md#processmainmodule
 [`punycode`]: punycode.md