docs: user's manual documentation on the Persistent PinUvAuthToken (PPUAT)

[equijano21]

Description

Added new documentation on the Persistent PinUvAuthToken (PPUAT) to the FIDO2 section of the User's Manual.

How has this been tested?

Local docs build

[DennisDyallo]

No objections here. Thanks for this @equijano21

[github-actions]

Test Results: Windows

    2 files      2 suites   15s ⏱️
4 027 tests 4 008 ✅ 19 💤 0 ❌
4 029 runs  4 010 ✅ 19 💤 0 ❌

Results for commit 3a8e7f3.

[github-actions]

Test Results: Ubuntu

    2 files      2 suites   43s ⏱️
4 019 tests 4 000 ✅ 19 💤 0 ❌
4 021 runs  4 002 ✅ 19 💤 0 ❌

Results for commit 3a8e7f3.

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
Yubico.Core	45%	35%	4557	➖
Yubico.YubiKey	51%	47%	21111	➖
Summary	50% (37315 / 74784)	45% (9080 / 20289)	25668	➖

Minimum allowed line rate is 40%

[github-actions]

Test Results: MacOS

    4 files      4 suites   23s ⏱️
4 001 tests 4 001 ✅ 0 💤 0 ❌
4 003 runs  4 003 ✅ 0 💤 0 ❌

Results for commit 3a8e7f3.

[equijano21]

@DennisDyallo I added a couple more commits. I think I've covered everything on PPUATs now--let me know if any changes are needed.

[DennisDyallo]

Thanks, it looks good. Feel free to merge and deploy