Update preview instructions, spelling, and deprecated contact

[zc-hmcts]

Update README to include:

• an introduction
• up to date instructions on developing remotely. GitPod is no longer an in-browser IDE and costs £ so set up Codespaces
• Local development - tested on non-admin macbook also

Also updated:

• British spelling throughout
• finops contact detail
• added dev container config. to be used with Codespaces or optionally locally.

[github-actions]

@check-spelling-bot Report

🔴 Please review

See the 📂 files view, the 📜action log, or 📝 job summary for details.

Unrecognized words (1)

devcontainers

To accept these unrecognized words as correct, you could run the following commands

... in a clone of the git@github.com:hmcts/hmcts.github.io.git repository
on the zc_updates branch (ℹ️ how do I use this?):

curl -s -S -L 'https://raw.githubusercontent.com/check-spelling/check-spelling/v0.0.23/apply.pl' |
perl - 'https://github.com/hmcts/hmcts.github.io/actions/runs/28666098903/attempts/1'

Warnings (1)

See the 📂 files view, the 📜action log, or 📝 job summary for details.

⚠️ Warnings	Count
⚠️ no-newline-at-eof	1

See ⚠️ Event descriptions for more information.

---

🖊️ Please consider adding a word to the allow list if it is flagged as a spelling error but is genuinely used within the project.
🤔 Think we might see a flagged mistake in another PR in the future? Please consider adding it as an expected pattern.