Recover past articles on channel blog

[pascalchevrel]

We deleted the old Channel blog however I discovered that we actually had good articles articles there linked from the wiki.

I updated the links in our wiki to point to the Wayback Machine snapshot:

• http://web.archive.org/web/20160417051846/https://blog.mozilla.org/channels/2011/06/01/more-details-about-how-to-use-the-tracking-firefox-bugzilla-flag/
• http://web.archive.org/web/20171012150350/https://blog.mozilla.org/channels/2011/07/18/every-six-weeks/

We should probably rewrite/update those and either put them on the current blog or turn them into wiki pages.