doc: add steps about signing the binary in single-executable docs
requested to merge github/fork/RaisinTen/doc-add-steps-about-signing-the-binary-in-single-executable-docs into main
We didn't catch this in https://github.com/nodejs/node/pull/45038 because the binary wasn't signed by default unlike the official Node.js binary, which is signed by the Node.js Foundation identity by default.
Refs: https://github.com/nodejs/postject/issues/76 (macOS arm64 part only) Fixes: https://github.com/nodejs/postject/issues/75
cc @nodejs/single-executable @targos @ShenHongFei