feat(release): support alpha releases

components/git/release.js

@@ -85,6 +85,8 @@ export function builder(yargs) {
       'Prepare a new security release of Node.js with auto-determined version')
     .example('git node release --prepare --newVersion=1.2.3',
       'Prepare a new release of Node.js tagged v1.2.3')
+    .example('git node release --prepare --newVersion=27.0.0-alpha.1.0.0',
+      'Prepare a new Alpha release of Node.js tagged v27.0.0-alpha.1.0.0')
     .example('git node release --promote https://github.com/nodejs/node/pull/12345 https://github.com/nodejs/node/pull/54321',
       'Promote two prepared releases of Node.js with PR #12345 and #54321')
     .example('git node --prepare --startLTS',

docs/git-node.md

@@ -243,6 +243,21 @@ git node release --prepare 1.2.3
 git node release --prepare
 ```
 
+```sh
+# Prepare an Alpha release of Node.js. Alpha release lines are detected from
+# the NODE_ALPHA_*_VERSION macros in src/node_version.h, and the alpha
+# version is automatically determined when no version is given. When the
+# release line has no CHANGELOG_VN.md yet, the first release
+# (N.0.0-alpha.0.0.0) creates it from the commits that are not on vN-1.x.
+git node release --prepare 27.0.0-alpha.1.0.0
+```
+
+```sh
+# Prepare the semver-major release of an Alpha release line, which marks it
+# as out of Alpha.
+git node release --prepare 27.0.0
+```
+
 ```sh
 # Prepare the first LTS release for a given release line
 git node release --prepare --startLTS