Update Vuforia Android instructions

[codebyrpp]

Description

The README file was updated to include instructions for integrating Vuforia Android. Key changes involve creating a new directory, modifying specific gradle files, and handling dependencies in the Unity project. Post-export steps are provided, ensuring proper integration after each Unity project export. This PR will likely solve the following issue #689,

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[timbotimbo]

Thanks for the contribution, the Vuforia instructions were indeed outdated and broken.

I will try to make a build following these instructions soon.

These Vuforia docs might also be useful to link, in case this breaks again in the future.
https://library.vuforia.com/unity-extension/using-vuforia-engine-unity-library-uaal#ios-specific-steps
They aren't an exact match to this pugin, but should get people on the right track.

[Update} Sorry for the delay in 'soon', I'm still planning to test this but stuff got in the way.

[timbotimbo]

@rajivaPavan

I just did a test on android using Unity 2022.3.20 and Vuforia 10.21, and I believe your instructions might be redundant.

I decided to follow the vuforia instructions that only mention using flatDir, which this plugin already uses. So I did not make any changes at all.

An image target from the example database worked on the first try. Indeed I did not need to make any gradle changes after the standard unity export.

Since the instructions mention 2021.3, I assume this isn't limited to only the very latest versions.