Fix Octokit#meta api doc link

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Add API doc url to Emojis#emojis

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Fix Statuses doc urls

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Add doc url to Octokit#update_user

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Fix doc urls in Refs module

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Add doc url for #delete_pull_request_comment

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Add doc urls to PubSubHubbub

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Fix doc urls in Objects module

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Fix #markdown doc url

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Fix doc urls in Labels module

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Fix doc url for #issue_comments

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Add doc url for #available_hooks

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Remove irrelevant doc url from #gitignore_templates
Add doc url to #starred_gists

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Fix doc urls in Contents module

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Fix doc urls in Commits module

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Fix doc urls in CommitComments module

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Merge pull request #362 from joeyw/doc-fixes

Doc fixes