fix doc url

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Update CONTRIBUTING.md
Merge pull request #365 from joeyw/fix-doc-url

fix doc url
Unset auth variables in ENV for testing.
Merge pull request #367 from joeyw/unset-access-tokens-for-test

Unset auth variables in ENV for testing.
fix doc url in milestones

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fix doc url in pull requests

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fix doc url in repositories

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fix doc url in downloads

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fix doc url in repositories

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fix doc url in releases

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fix doc urls in users

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fix doc urls in organizations

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fix doc url in rate_limit

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fix doc example in objects

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add doc url in events

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Merge pull request #369 from joeyw/doc-fixes

docs docs docs
fix doc url in repositories

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fix doc url in users

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add doc url in issues

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