update instructions for building arm versions of re2

src/dev/build/tasks/patch_native_modules_task.ts

@@ -54,24 +54,34 @@ const packages: Package[] = [
         sha256: '4d06747b266c75b6f7ced93977692c0586ce6a52924cabb569bd966378941aa1',
       },
 
-      // ARM build is currently done manually as Github Actions used in upstream project
+      // ARM builds are currently done manually as Github Actions used in upstream project
       // do not natively support an ARM target.
 
-      // From a AWS Graviton instance:
-      // * checkout the node-re2 project,
-      // * install Node using the same minor used by Kibana
-      // * git submodule update --init --recursive to download re2
-      // * npm install, which will also create a build
-      // * gzip -c build/Release/re2.node > linux-arm64-83.gz
-      // * upload to kibana-ci-proxy-cache bucket
+      // From a AWS Graviton instance running Ubuntu:
+      // * install build-essential package
+      // * install nvm and the node version used by the Kibana repository
+      // * `npm install [email protected]`
+      // * re2 will build itself on install
+      // * `cp node_modules/re2/build/Release/re2.node > linux-arm64-$(node -e "console.log(process.versions.modules)")
+      // * `gzip linux-arm64-*`
+      // * capture the sha256 with: `shasum -a 256 linux-arm64-*`
+      // * upload the `linux-arm64-*.gz` artifact to the `yarn-prebuilt-assets` bucket in GCS using the correct version number
       'linux-arm64': {
         url: 'https://us-central1-elastic-kibana-184716.cloudfunctions.net/kibana-ci-proxy-cache/node-re2/uhop/node-re2/releases/download/1.17.4/linux-arm64-93.gz',
         sha256: '25409584f76f3d6ed85463d84adf094eb6e256ed1cb0b754b95bcbda6691fc26',
       },
+
+      // A similar process is necessary for building on ARM macs:
+      // * bootstrap and re2 will build itself on install
+      // * `cp node_modules/re2/build/Release/re2.node > darwin-arm64-$(node -e "console.log(process.versions.modules)")
+      // * `gzip darwin-arm64-*`
+      // * capture the sha256 with: `shasum -a 256 darwin-arm64-*`
+      // * upload the `darwin-arm64-*.gz` artifact to the `yarn-prebuilt-assets` bucket in GCS using the correct version number
       'darwin-arm64': {
         url: 'https://us-central1-elastic-kibana-184716.cloudfunctions.net/kibana-ci-proxy-cache/node-re2/uhop/node-re2/releases/download/1.17.4/darwin-arm64-93.gz',
         sha256: 'd4b708749ddef1c87019f6b80e051ed0c29ccd1de34f233c47d8dcaddf803872',
       },
+
       'win32-x64': {
         url: 'https://us-central1-elastic-kibana-184716.cloudfunctions.net/kibana-ci-proxy-cache/node-re2/uhop/node-re2/releases/download/1.17.4/win-x64-93.gz',
         sha256: '0320d0c0385432944c6fb3c8c8fcd78d440ce5626f7618f9ec71d88e44820674',