DOC: Further minor readme updates

Author: kernc

CONTRIBUTING.md

@@ -78,9 +78,12 @@ Pull requests
 -------------
 A general recommended reading:
 [How to make your code reviewer fall in love with you][code-review].
-Please use explicit commit messages. See [NumPy's development workflow]
+
+Use explicit commit messages — see [NumPy's development workflow]
 for inspiration.
 
+Every new feature must be accompanied by a unit test.
+
 Please help review [existing PRs] you wish to see included.
 
 [code-review]: https://mtlynch.io/code-review-love/

README.md

@@ -5,16 +5,16 @@ Backtesting.py
 [![Build Status](https://img.shields.io/github/actions/workflow/status/kernc/backtesting.py/ci.yml?branch=master&style=for-the-badge)](https://github.com/kernc/backtesting.py/actions)
 [![Code Coverage](https://img.shields.io/codecov/c/gh/kernc/backtesting.py.svg?style=for-the-badge)](https://codecov.io/gh/kernc/backtesting.py)
 [![Backtesting on PyPI](https://img.shields.io/pypi/v/backtesting.svg?color=blue&style=for-the-badge)](https://pypi.org/project/backtesting)
-[![PyPI downloads](https://img.shields.io/pypi/dd/backtesting.svg?color=skyblue&style=for-the-badge)](https://pypi.org/project/backtesting)
-[![Total downloads](https://img.shields.io/pepy/dt/backtesting?style=for-the-badge&label=%E2%88%91&color=skyblue)](https://pypi.org/project/backtesting)
+[![PyPI downloads](https://img.shields.io/pypi/dd/backtesting.svg?color=skyblue&style=for-the-badge)](https://pypistats.org/packages/backtesting)
+[![Total downloads](https://img.shields.io/pepy/dt/backtesting?style=for-the-badge&label=%E2%88%91&color=skyblue)](https://pypistats.org/packages/backtesting)
 [![GitHub Sponsors](https://img.shields.io/github/sponsors/kernc?color=pink&style=for-the-badge&label=%E2%99%A5)](https://github.com/sponsors/kernc)
 
 Backtest trading strategies with Python.
 
-[**Project website**](https://kernc.github.io/backtesting.py) + [Documentation]
+[**Project website**](https://kernc.github.io/backtesting.py) + [Documentation]   |  [YouTube]
 
 [Documentation]: https://kernc.github.io/backtesting.py/doc/backtesting/
-
+[YouTube]: https://www.youtube.com/?q=%22backtesting.py%22
 
 Installation
 ------------