Fix Markdown comments

[kroq-gar78]

The current Markdown comment, >, does not work in the pandoc implementation of Markdown. I am not aware of any implementation of Markdown that uses the > character as a comment symbol, especially since it is used by some implementations for quotation blocks, which is a completely different function (at least, I couldn't find any). Thus, the proposed implementation would work in at least some implementations.

[alerque]

Fork notice: With the upstream project sitting stale after nearly 8 months since the last activity, 71 outstanding pull requests, no comments from the original developer, and dozens of developers duplicating efforts while scratching their own itches, I've decided to step in and run a fork for a while. Hopefully the original developer will eventually consider picking this plugin up again or adding more maintainers so that the user base doesn't end up fragmented, but for now I would invite anyone interested in the latest updates to consider installing from and contributing pull requests to my fork.

About this PR: I have merged this PR as is. Please consider installing the plugin from alerque/nerdcommenter for this and (so far) over two dozen other updates.

Just a small note @kroq-gar78, next time please consider rebasing instead of merging upstream changes before submitting pull requests as that makes it a lot easier to review and keeps the resulting history cleaner.

[alerque]

Change of plans. Thanks to scrooloose who has added me as a maintainer to this repo, I'll be going through and taking care of business here instead of in a fork. I've cherry picked the main commit out of this PR branch and pushed it upstream. The other commit is obsolete.

Thanks for your contribution @kroq-gar78.

[aemonge]

Let me suggest a better comment for markdown..... i've research and it seams to be THE one :)

Hope it helps!

#333