[CLOSED] Styled the src/extensions README

[core-ai-bot]

Issue by ficristo
Sunday Feb 19, 2017 at 14:30 GMT
Originally opened as adobe/brackets#13113

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This is adobe/brackets#13011 but for all the README under src/extensions.
I renamed the files but git doesn't recognize the renames...

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ficristo included the following code: https://github.com/adobe/brackets/pull/13113/commits