Update 4-personalize-codespace.md

[RachBreeze]

Fixes for issues found whilst working on this training

Summary

Hello

Whilst working through this training I came across two issues, these have been documented by other people:

1. https://github.com/orgs/skills/discussions/607
2. https://github.com/skills/code-with-codespaces/issues/121

This PR updates the documentation to help resolve the issues

Changes

Closes:

1. https://github.com/orgs/skills/discussions/607
2. https://github.com/skills/code-with-codespaces/issues/121

Task list

• [ ] For workflow changes, I have verified the Actions workflows function as expected.
• [ ] For content changes, I have reviewed the style guide.