Update Playground documentation with current UI screenshots - #90

Running Vale across on the following files affected by this PR:

- features/playground.mdx

Attempting to initialize Vale linter...
No customer vale configuration detected. Using Mintlify's default configuration.
Attempting to run Vale spellcheck...
Vale spellcheck completed successfully.

features/playground.mdx:
	- 19:12     Did you really mean 'Testset'?
	- 20:21     Did you really mean 'Testset'?
	- 21:12     Did you really mean 'testset'?
	- 22:9      Did you really mean 'testsets'?
	- 23:18     Did you really mean 'testcases'?
	- 23:37     Did you really mean 'testset'?
	- 25:10     Did you really mean 'Testcases'?
	- 26:23     Did you really mean 'testcases'?
	- 27:43     Did you really mean 'testcases'?
	- 28:12     Did you really mean 'testcases'?
	- 29:44     Did you really mean 'testcase'?
	- 46:30     Did you really mean 'testcase'?
	- 61:66     Did you really mean 'testcases'?
	- 65:47     Did you really mean 'testcases'?
	- 66:59     Did you really mean 'testset'?
	- 70:49     Did you really mean 'testcase'?
	- 84:19     Did you really mean 'testcases'?
	- 85:11     Did you really mean 'testcases'?
	- 101:32    Did you really mean 'testcase'?
	- 103:33    Did you really mean 'testcases'?
	- 111:10    Did you really mean 'testcase'?
	- 115:12    Did you really mean 'testcases'?
	- 123:8     Did you really mean 'testset'?


Found 23 suggested changes across 1 files in 871.19ms