Create STG3684AU

[eclecticc]

Create STG3684AU Low voltage 0.5Ω max dual SPDT switch, QFN10L

Footprint in https://github.com/KiCad/kicad-footprints/pull/1981

https://www.st.com/resource/en/datasheet/stg3684a.pdf

---

All contributions to the kicad library must follow the KiCad library convention

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• [x] Provide a URL to a datasheet for the symbol(s) you are contributing
• [x] An example screenshot image is very helpful
• [x] Ensure that the associated footprints match the official footprint library
  • A new fitting footprint must be submitted if the library does not yet contain one.
• [x] If there are matching footprint PRs, provide link(s) as appropriate
• [x] Check the output of the Travis automated check scripts - fix any errors as required
• [x] Give a reason behind any intentional library convention rule violation.