feat: Multiple changes to core files.

[bvanelli]

• Introduce issue templates for Github (closes https://github.com/bvanelli/actualpy/issues/28)
• Fix command to install directly from git (closes https://github.com/bvanelli/actualpy/issues/33)
• Add documentation on how to install new transactions and run rules
• Add example on how to import a CSV file
• Small fixes to the Gnucash import

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.53%. Comparing base (d79c930) to head (3754c99).

Files	Patch %	Lines
actual/queries.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #34 +/- ## ========================================== + Coverage 96.45% 96.53% +0.07% ========================================== Files 12 12 Lines 1691 1701 +10 ========================================== + Hits 1631 1642 +11 + Misses 60 59 -1 ```

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