"yarn setup" - the new way to install your deps (#10379)

* deps - run "yarn setup" to install deps

* doc - add "yarn setup" to local dev instructions

README.md

@@ -20,7 +20,7 @@ To learn how to contribute to the MetaMask project itself, visit our [Internal D
 - Install [Node.js](https://nodejs.org) version 14
     - If you are using [nvm](https://github.com/creationix/nvm#installation) (recommended) running `nvm use` will automatically choose the right node version for you.
 - Install [Yarn](https://yarnpkg.com/en/docs/install)
-- Install dependencies: `yarn`
+- Install dependencies: `yarn setup` (not the usual install command)
 - Copy the `.metamaskrc.dist` file to `.metamaskrc`
     - Replace the `INFURA_PROJECT_ID` value with your own personal [Infura Project ID](https://infura.io/docs).
     - If debugging MetaMetrics, you'll need to add a value for `SEGMENT_WRITE_KEY` [Segment write key](https://segment.com/docs/connections/find-writekey/).

package.json

@@ -3,6 +3,7 @@
   "version": "0.0.0",
   "private": true,
   "scripts": {
+    "setup": "yarn install && yarn allow-scripts",
     "start": "yarn build dev",
     "dist": "yarn build prod",
     "build": "node development/build/index.js",