Update Treasury Links within Training Lessons

[john-labbate]

Describe the bug
Update the following training links

To Reproduce

training purchase lesson 1 - "What are the regulations that govern the use of the purchase card/account?"
training purchase lesson 5 - "What are Government-to-Government transactions?"
training purchase PC lesson 3 - "What are Government-to-Government transactions?"

To the following
Lesson 1: https://tfx.treasury.gov/tfm/volume1/part4/chapter-4500-government-purchase-cards
Lesson 5: https://tfx.treasury.gov/tfm/volume1/part5/chapter-7000-credit-and-debit-card-collection-transactions
PC Lesson 3: https://tfx.treasury.gov/tfm/volume1/part5/chapter-7000-credit-and-debit-card-collection-transactions

[JennaySDavis]

647 Acceptance Criteria

Pass/Fail	Description
Pass	Lesson 1: https://tfx.treasury.gov/tfm/volume1/part4/chapter-4500-government-purchase-cards
Pass	Lesson 5: https://tfx.treasury.gov/tfm/volume1/part5/chapter-7000-credit-and-debit-card-collection-transactions
Pass	PC Lesson 3: https://tfx.treasury.gov/tfm/volume1/part5/chapter-7000-credit-and-debit-card-collection-transactions

Comments/Additional Notes
N/A

ADA Compliance (Automated scan via Chrome Lighthouse)

Criteria	Score
Performance	100
Accessibility	100
Best Practices	100

Passed 09/18/2024 - JSD