Ediatable configs without risk of versioning + Getting started instructions in README

[confusedmatrix]

Pull Request

Description

• Moves the existing default configs to configs.example directory
• Users are now expected to copy this to configs directory (which is gitignored to prevent versioning)
• Adds instructions for new users to PVNet to help get up and running, including advice on sourcing datasets for use with PVNet

How Has This Been Tested?

Ran through new instructions from scratch to ensure accuracy

• [x] Yes

If your changes affect data processing, have you plotted any changes? i.e. have you done a quick sanity check?

• [ ] Yes

Checklist:

• [x] My code follows OCF's coding style guidelines
• [x] I have performed a self-review of my own code
• [x] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [x] I have checked my code and corrected any misspellings

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (fe30469) 50.85% compared to head (48a282a) 50.85%. Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #106 +/- ## ======================================= Coverage 50.85% 50.85% ======================================= Files 26 26 Lines 1701 1701 ======================================= Hits 865 865 Misses 836 836 ```

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[peterdudfield]

@dfulu can you have a look at this?