chore(docs): Add error FAQs to docs

[benmvp]

Problem

I was setting up babel-plugin-react-css-modules (with React Storybook) and ran into a number of errors. And because I wasn't quite sure how this plugin worked, I wasn't quite sure how to fix the errors. Three days later the docs make way more sense did they did.

Solution

I've proposed a number of doc tweaks as well as a couple of new FAQ issues around the errors I was running into w/ proposed solutions. The solutions also give more insight into how the plugin works so that other folks using the plugin can inform themselves to hopefully solve their problems as well.

Notes

• I wanted to reformat the Options table because it's a nightmare to read because of the horizontal scrolling, but I left that out
• I saw a lot of StackOverflow questions with folks posting their .babelrc including postcss-nested with postcss-scss. I believe it's not needed because SCSS already supports nesting. I assume folks have that in their code because the example includes it. I couldn't think of a good additional plugin to pair, so I added an FYI note.

[benmvp]

Thanks for the quick merge!