update readme with publishing info

Author: greggman

.gitignore

@@ -1,5 +1,6 @@
 *.pyc
 .DS_Store
+.vscode
 node_modules
 third_party/package.json
 

PUBLISHING.md

@@ -0,0 +1,36 @@
+# PUBLISHING
+
+node-webgpu is auto published via github actions to npm whenever a tag
+is pushed to the repository.
+
+The steps in general are:
+
+```bash
+git remote add upstream git@github.com/dawn-gpu/node-webgpu.git
+# update the repo
+# run the tests
+npm version patch # or minor or major
+git push --tag upstream main
+```
+
+That should build all 3 platforms and then publish a new package
+on npm. At the time of this writing that generally takes 20-30 minutes.
+
+## Notes
+
+### No tests on CQ
+
+github actions doesn't currently run any tests as there is no GPU
+so run tests locally before pushing the patch.
+
+### npm permissions
+
+The github action publishes to npm via the `JS-DevTools/npm-publish`
+action. See `.github/workflows/build.yml`. This uses github
+secret named `NPM_TOKEN` which is stored and unrecoverable in
+the repo's settings. To change it, an admin of this project,
+and of the npm project would go to npm, generate a new token,
+then copy it into the github settings for this project.
+
+* getting a token for npm: https://docs.npmjs.com/creating-and-viewing-access-tokens
+* adding secret to github: https://docs.github.com/en/actions/security-for-github-actions/security-guides/using-secrets-in-github-actions

README.md

@@ -220,6 +220,10 @@ And you must have `node.js` installed, at least version 18.
 I recommend using [nvm](https://github.com/nvm-sh/nvm) to install it
 as it makes it easy to switch versions.
 
+## Publishing
+
+See [PUBLISHING.md](PUBLISHNG.md).
+
 ## License
 
 MIT: https://dawn.googlesource.com/dawn/+/HEAD/LICENSE