DOC: add SysIdentPy to users

closes gh-671

Author: lucascolley

README.md

@@ -36,8 +36,9 @@ Used by:
 
 - [SciPy](https://github.com/scipy/scipy) — Fundamental algorithms for
   scientific computing.
-- [scikit-learn](https://github.com/scikit-learn/scikit-learn) — Machine
+- [scikit-learn](https://github.com/scikit-learn/scikit-learn) — Machine
   Learning in Python.
+- [SysIdentPy](https://github.com/wilsonrljr/sysidentpy) — System Identification Using NARMAX Models
 - *your library? Let us know!*
 
 ## Installation

docs/index.md

@@ -27,6 +27,7 @@ It is currently used by:
   scientific computing.
 - [scikit-learn](https://github.com/scikit-learn/scikit-learn) — Machine
   Learning in Python.
+- [SysIdentPy](https://github.com/wilsonrljr/sysidentpy) — System Identification Using NARMAX Models
 - *your library? Let us know!*
 
 (installation)=