### changes
#### remove trailing spaces
When I was using example I noticed trailing spaces.
So, this PR removes the trailing spaces of json file, README, and others.
`examples/with-jest-typescript/src/modules/cars/Overview.tsx` also has it, but this time it did not change as tslint error occurs at commit.
* Examples: clarify language around Yarn create & npx
* add missing READMEs and create-next-app usage
* suggest people tag jthegedus in firebase related issues
* add yarn alt instructions
* cerebraljs example readme & fixes
* remove global npm install of create-next-app
* add npx to create-next-app command in examples
* add bash to shell snippets
* add yarn create to next-app command in examples
* fix READMEs named with lowercase
* change READMEs to use UPPERCASE
