Add a standard .gitignore to the template

[ashryanbeats]

There are some good ones already out in the universe.

Bare minimum, include:

.env
node_modules

[ashryanbeats]

Example:
https://github.com/expressjs/generator/blob/master/templates/js/gitignore

[ashryanbeats]

Kitchen sink:
https://github.com/github/gitignore

Maybe we can leverage this in some way?

[relaxedtomato]

For now, just consolidated our existing code samples .gitignores which includes .env and node_modules.

We should be good to close the issue.