specify node version for PKCE angular project

[NatnaelSisay]

While running the application in the latest version of node the application keeps crashing and the error message was not helpful. The i have found out about angular and its node version compatibility from StackOverflow, and after downgrading my node version to "node": "^12.14.0" the application started working.

So my suggestion is to put

...
"engines": {
    "node": "^12.14.0"
}

in package.json file to indicate which version of node the application was built on.

Thank you.