docs: Add logo

[bennycode]

Checklist for new indicators

• [ ] Indicator is documented and implemented by extending BigIndicatorSeries
• [ ] A "faster" version of this indicator is implemented by extending NumberIndicatorSeries
• [ ] Tests for getResult are present
• [ ] Tests for highest and lowest result caching are present (if not already existent for base class)
• [ ] Tests for error handling are present (if not already existent for base class)
• [ ] Indicators (standard & faster version) are exposed in src/index.ts
• [ ] Indicators (standard & faster version) are added to startBenchmark.ts
• [ ] Indicator is listed in README.md