Add Local Dev Setup instructions to Contributors.md (mono repo)

[MichaelDimmitt]

Describe the bug
Currently undocumented.

Expected behavior
Should be able to clone down the project, trouble shoot, and see your changes in a debug environment.

Starting place: What worked for myself macbook computer

Base level get everything setup

git clone https://github.com/yoavbls/pretty-ts-errors.git;
cd pretty-ts-errors;
git checkout feature/107-button-to-open-error-in-new-tab;
npm install
npm install --workspaces
npm run build --workspaces

Outstanding known issues: #158

Run dev and debug to spin up a vscode instance that is watching the extension.

1. Run: npm run dev from either paths:
   pretty-ts-errors/apps/vscode-extension/package.json or pretty-ts-errors/package.json

Generate vsix file:

1. Run: npm run build from either paths:
   pretty-ts-errors/apps/vscode-extension/package.json or pretty-ts-errors/package.json
2. Take note of the vsix path that is output in terminal from the build command.
3. Go to the extensions tab of the vscode instance you want to import the extension into.
4. Select the ... - views and more actions section.
5. Click install from vsix

Need a profile without any extensions?

Here is how I was debugging the project:

1. Image showing how to create a new profile:

2. Alternatively, Command + Shift + P and type Profile: New Profile

[kevinramharak]

The profile is a good addition, I did not know that. I tend to use the launch configuration that says Run Extension (all extensions disabled). It will start vscode with the --disable-extensions flag which will automatically disable all user installed extensions.

I will use this info to update the CONTRIBUTING.md, as especially with the monorepo this is a little more complex now.