Create FAQ.md

[hassankhan]

This is a Feature Proposal

Description

There are quite a few recurring issues that people seem to have when using the plugin, it would be really helpful to point users to a document where they can find a solution/workaround.

Issues

Handler import errors

• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/43#issuecomment-286584687
• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/43#issuecomment-411158444
• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/459#issuecomment-450749257

Source maps

• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/446#issuecomment-429479152

Dynamic imports

• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/477#issuecomment-477099937

Native Modules

• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/386#issuecomment-392465439

Node Externals

• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/483#issuecomment-478723461
• [x] #494

Multilanguage projects

• [ ] https://github.com/serverless-heaven/serverless-webpack/issues/255#issuecomment-471982085

Monorepo projects

• [ ] #430