Add KeePassDX icon

[admvx]

Trickier one! 😅 Addresses #374

• New file which is under 1,024 bytes
• Edit Readme
• Add reference image
• Edit reference page
• Android Image

[edent]

Amazing use of feDropShadow! I don't think we've had one of those before.

I'm granting you commit access to the Repo. This is per the advice of The Pull Request Hack.

Please use this privilege wisely.

[admvx]

Thank you @edent! I'll absolutely take the responsibility seriously – and I admire the philosophy of the linked post.

I must admit I had no cause to use feDropShadow before either 😁 Thanks again