Update README.md

More options for Unmarshal (#8)

* defaults from code

* allow loading environment variables from a file to aid in docker secrets

* no need to Unset

assert one last test before release

Error signature refactoring (#6)

- Refactors to a `val, err := Get("ENV")` based signature
- Changes most functions to a `val, err` signature to match this
- Breaks code into functional files for sanity
- Provides `Get` alias `GetString` for convention
- Renames `GetSlice` to `GetStringSlice` and supports more types
- Adds support for multiple `default` slice values through `default=[one,two,three]`
  - Does not require the brackets if there is only 1 default item.

further test coverage

Merge pull request #3 from syntaqx/unmarshal

Unmarshal & Updates

Merge pull request #2 from john-peterson-g17/add-comma-list

Add functionality for parsing comma list value into a slice of strings

Merge branch 'main' of github.com:syntaqx/env

wrap godotenv for load/overload for now; include documentation on usage

reorder readme