DOC: Add "AutoTrader" to alternatives.md (#696)

This commit adds AutoTrader to the alternatives document with an
associated description and links to relevant backtesting documentation.

Co-authored-by: Jack McPherson <[email protected]>

Author: jmcph4

doc/alternatives.md

@@ -10,6 +10,9 @@ If after reviewing the docs and examples perchance you find
 [_Backtesting.py_](https://kernc.github.io/backtesting.py) not your cup of tea,
 kindly have a look at some similar alternative Python backtesting frameworks:
 
+-  [AutoTrader](https://github.com/kieran-mackle/AutoTrader) -
+  an automated trading framework with an emphasis on cryptocurrency markets
+  that includes a [robust backtesting API](https://github.com/kieran-mackle/AutoTrader/blob/main/docs/source/tutorials/backtesting.md)
 - [bt](http://pmorissette.github.io/bt/) -
   a framework based on reusable and flexible blocks of
   strategy logic that support multiple instruments and