Code Editor - add documentation how to use JSON Schemas

[nicolethoen]

It is not super straight forward to get the beforeMount call to cooperate with yaml parsing and many people using our code editor are using it for parsing/editing yaml files.

it might be wise to add an example which includes yaml parsing. A working example in a codebase is in this PR: https://github.com/KaotoIO/kaoto/pull/1179/files#diff-c64390323d50afca275373be6b4e3da7e76d1faefb849499e4aa47ae537c7b36

This request originates from this slack thread.