Polish Chapter 1 wording and standards references

[Walentalien]

This PR applies a first editorial pass across Chapter 1 (Foundation) with high-confidence wording and consistency fixes.

Summary of changes:

• Clarify grammar and phrasing in foundation/problem.rst, foundation/software.rst, and foundation/trend.rst.
• Fix a grammar issue in foundation/architecture.rst ("more than one protocol").
• Correct standards references in foundation/architecture.rst:
  • IEEE 802.3 Ethernet + 802.11 Wi-Fi
  • ITU-T H.264 video encoding standard
• Fix missing terms in foundation/performance.rst (adds missing latency, RTT, and link in transfer-time discussion).

Validation:

• Ran make spelling successfully (existing repo-wide spelling warnings remain unchanged).

[drbruced12]

Thanks again. I think H.232 might have been a typo for H.323, but H.264 works well given that we call out video specifically. You've also found a family of bugs from the 5E->6E conversion in which some words that were formatted as sans serif got dropped altogether - hence the missing words in a few cases.