Add GitHub account security documentation (PDF)

[inaambaj]

Please check the following - and then delete this message:

• If you are creating a new page, does it contain the following value at the top, with x being the position in the folder?

---
sidebar_position: x
---

• If you are creating a new sub-folder, does it have a _category_.json file with the appropriate descriptive information?
• Are all your images / videos named appropriately and in the correct location ("image1.png" e.g. will not be accepted)
• Are all your code blocks properly closed off?
• Does your file have an appropriate and descriptive file name, and main header?
• Ensure all files are referenced correctly (They are case sensitive - if you save "image.png" you cannot reference "Image.PNG")

Failure to include these will result in your request not being reviewed.

[raymondchoy14]

good to go