doc: add a sentence about REPLACEME in code changes

When adding to the REPL API recently, I was unsure what to put as a
version number for the new method I added. This change adds a reference
to `releases.md` where the use of `REPLACEME` is discussed.

PR-URL: #25961
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

doc/guides/contributing/pull-requests.md

@@ -116,7 +116,8 @@ time to ensure that the changes follow the Node.js code style guide.
 Any documentation you write (including code comments and API documentation)
 should follow the [Style Guide](../../STYLE_GUIDE.md). Code samples included
 in the API docs will also be checked when running `make lint` (or
-`vcbuild.bat lint` on Windows).
+`vcbuild.bat lint` on Windows). If you are adding to or deprecating an API,
+use `REPLACEME` for the version number in the documentation YAML.
 
 For contributing C++ code, you may want to look at the
 [C++ Style Guide](../../../CPP_STYLE_GUIDE.md).