Add text highlight for Javascript on debugging section

[andersonaguiar]

Set a highlighted text for a smooth read, following the same pattern as per the README.

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[andersonaguiar]

@googlebot I signed it!

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[mathiasbynens]

please indent

[mathiasbynens]

Adding the backticks for syntax highlighting sounds great!
However, these backticked blocks must still be indented with 4 spaces so that they become part of the list item, instead of interrupting the list. Could you please make these changes?

[andersonaguiar]

Good observation, fixed.