Add render on content change

[howtodoappdevelopment]

Examples: p.et-p.ml-0>span.content{## test} -> to h2 p.et.p.ml-3>span.content{**test**} -> to p>span>b{test} p.et-p.ml-0>span.content{```} + enter -> create precode h1.et-h1>span.sign{#}+span.content{### } -> do nothing