docs: make folder tree for split command in quick start more readable

[bandantonio]

What/Why/How?

Incorrect formatting of the ASCII folder tree makes it hard to skim and understand

Reference

https://redocly.com/docs/cli/quickstart/#split---divide-your-large-definition-into-smaller-parts

Testing

Screenshots (optional)

Check yourself

• [ ] Code is linted
• [ ] Tested with redoc/reference-docs/workflows
• [ ] All new/updated code is covered with tests

Security

• [ ] Security impact of change has been considered
• [ ] Code follows company security practices and guidelines

[github-actions[bot]]

Coverage report

Total coverage

Status	Category	Percentage	Covered / Total
🟡	Statements	67.1%	2745/4091
🟡	Branches	60.06%	1505/2506
🔴	Functions	58.37%	436/747
🟡	Lines	67.36%	2547/3781

Status of coverage: 🟢 - ok, 🟡 - slightly more than threshold, 🔴 - under the threshold

Report generated by 🧪jest coverage report action from 46efdc906ad6520abce286d769788df1b3dd7c8f

[lornajane]

This one has been around a while, rebasing

[github-actions[bot]]

Coverage report

St.:grey_question:	Category	Percentage	Covered / Total
🟡	Statements	73.73%	3450/4679
🟡	Branches	64.72%	1965/3036
🟡	Functions	65.98%	580/879
🟡	Lines	73.75%	3208/4350

Test suite run success

571 tests passing in 85 suites.

Report generated by 🧪jest coverage report action from 07c51210c059f5d6af34415a628531dd58cfc6a2