chore(docs): update docs (#4125)

docs/local-development.md

@@ -3,15 +3,56 @@
 This document serves to give tips and tricks on how to run Renovate locally to add features or fix bugs.
 Please submit PRs to improve it if you think anything is unclear or you can think of something that should be added.
 
+## General notes
+
+We are currently migrating to [typescript](https://www.typescriptlang.org), so please write all new files as `ts` files
+and feel free to help us to convert existing files.
+
+If you have to modify existing `js` files, please use modern [esm](https://nodejs.org/api/esm.html) `imports`
+and `exports`. We will transpile them to `commonjs` on build.
+
 ## Install
 
+#### Prerequisites
+
+For local development some dependencies are required.
+
+- git
+- nodejs `^10.13.0 || ^12.0.0`
+- yarn `^1.17.0`
+- c++ compiler
+- python `^2.7`
+
+_Linux_
+
+You can use the following commands for `Ubuntu`.
+
+```sh
+curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -
+curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -
+echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list
+sudo apt-get update
+sudo apt-get install -y git python-minimal build-essential nodejs yarn
+```
+
+_Windows_
+
+You can use `powershell` and [chocolatey](https://chocolatey.org) to manage required dependencies on `Windows`.
+
+```ps
+Set-ExecutionPolicy Bypass -Scope Process -Force; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))
+cinst git node-lts yarn python2 visualstudio2017buildtools
+```
+
+If you have build error, you have to [configure](https://github.com/nodejs/node-gyp#on-windows) `node-gyp` to use the right tools.
+
 #### Fork and Clone
 
 If you will contribute to the project, you should first "fork" the main project using the GitHub Website and then clone your fork locally.
 
 #### Node version
 
-Renovate supports Node.js `>= 10.13.0 <11.0.0`. Use a version manager like `nvm` or `n` if you'll need to switch between versions easily.
+Renovate supports Node.js `^10.13.0 || ^12.0.0`. Use a version manager like `nvm` or `n` if you'll need to switch between versions easily.
 
 #### Install dependencies
 
@@ -52,7 +93,7 @@ If this is working then in future you can create other test repos to verify your
 
 ## Tests
 
-You can run `yarn test` locally to test your code. We test all PRs using the same tests, run on TravisCI. `yarn test` runs an `eslint` check, a `prettier` check, and then all the unit tests using `jest`.
+You can run `yarn test` locally to test your code. We test all PRs using the same tests, run on CircleCI and Azure Pipelines. `yarn test` runs an `eslint` check, a `prettier` check, a `type` check and then all the unit tests using `jest`.
 
 ## Jest