Doc update: Open AI -> OpenAI

[wangchao1230]

Description

Make follow up change with this: #3351

All Promptflow Contribution checklist:

• The pull request does not introduce [breaking changes].
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.
• Create an issue and link to the pull request to get dedicated review from promptflow team. Learn more: suggested workflow.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

promptflow SDK CLI Azure E2E Test Result clwan/fix_open_ai_typo

  4 files    4 suites   4m 19s ⏱️
244 tests 204 ✅  40 💤 0 ❌
976 runs  816 ✅ 160 💤 0 ❌

Results for commit e2cc32a.

[github-actions]

SDK CLI Global Config Test Result clwan/fix_open_ai_typo

6 tests   6 ✅  1m 18s ⏱️
1 suites  0 💤
1 files    0 ❌

Results for commit e2cc32a.

[github-actions]

promptflow-core test result

0 tests  ±0   0 ✅ ±0   0s ⏱️ ±0s
0 suites ±0   0 💤 ±0 
0 files   ±0   0 ❌ ±0 

Results for commit e2cc32a. ± Comparison against base commit 634ad8b.

[github-actions]

promptflow-evals test result

   12 files  ±0     12 suites  ±0   20m 26s ⏱️ +13s
   84 tests ±0     84 ✅ ±0  0 💤 ±0  0 ❌ ±0 
1 008 runs  ±0  1 008 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit e2cc32a. ± Comparison against base commit 634ad8b.

[github-actions]

Executor Unit Test Result clwan/fix_open_ai_typo

796 tests   796 ✅  3m 46s ⏱️
  1 suites    0 💤
  1 files      0 ❌

Results for commit e2cc32a.

[github-actions]

Executor E2E Test Result clwan/fix_open_ai_typo

246 tests   240 ✅  5m 5s ⏱️
  1 suites    6 💤
  1 files      0 ❌

Results for commit e2cc32a.

[github-actions]

SDK CLI Test Result clwan/fix_open_ai_typo

    4 files      4 suites   1h 6m 36s ⏱️
  786 tests   763 ✅ 23 💤 0 ❌
3 144 runs  3 052 ✅ 92 💤 0 ❌

Results for commit e2cc32a.