text: Title: Bollinger Bands Bandwidth
  Body: **Which version are you running? The lastest version is on Github. Pip is for major releases.**
  ```python
  import pandas_ta as ta
  print(ta.version)
  ```
  Version: 0.2.xxb
  
  **Upgrade.**
  ```sh
  $ pip install -U git+https://github.com/twopirllc/pandas-ta
  ```
  Yup.
  
  **Is your feature request related to a problem? Please describe.**
  Bollinger Bands Bandwidth
  
  **Describe the solution you'd like**
  [Bollinger Bands Bandwidth](https://www.sierrachart.com/index.php?page=doc/StudiesReference.php&ID=135&Name=Bollinger_Bands_-_Bandwidth)
  
  **Describe alternatives you've considered**
  None
  
  **Additional context**
  None