Edited GUI Category and added Bluetooth category

[Sakth1]

This PR is to correct hyperlinks in GUI Development and to add Bluetooth

Edited GUI category: In the GUI category, Edited the hyperlink of PyQt's docs which led to PySide's docs and added PySide to the list. PySide is the official binding from the QT company, while PyQT is the binding from a different company called riverbank. Both are ultimately the same with different name and licensing.

Added Bluetooth category: Added a category for Bluetooth, listing libraries to work with Bluetooth/BLE

Also added Hugging face to the machine learning category.

[Sakth1]

@vinta Can you please take a look at this PR.