docs-bug(harness): Add dist folder of harness examples to .gitignore

[Totati]

Documentation Feedback

Can't fork or save forked harness example once it compiles and runs. I can't save it because it gets too big.
Adding the dist folder to .gitignore does fix the problem.

20260918-0822-29.5558429.mp4

Affected documentation page

https://material.angular.dev/components/dialog/examples#dialog-harness

[crisbeto]

Weird, I wouldn't have expected the dist directory even show up there.