Change docs site structure

[hadarhg]

Change site structure:

• 'Use' becomes 'Get Started'
• 'Learn' becomes 'Documentation'
• 'Contribute' - stays the same
• 'Blog' - stays the same
• 'Project' - delete the tab and move content to 'Contribute' section

[asfbot]

Refer to this link for build results (access rights to CI server needed):
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[asfbot]

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Jenkins built the site at commit id 04e2855 with Jekyll and staged it here. Happy reviewing.

Note that any previous site has been deleted. This staged site will be automatically deleted after its TTL expires. Push any commit to the pull request branch or re-trigger the build to get it staged again.

[asfbot]

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[asfbot]

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Jenkins built the site at commit id 24f0b18 with Jekyll and staged it here. Happy reviewing.

Note that any previous site has been deleted. This staged site will be automatically deleted after its TTL expires. Push any commit to the pull request branch or re-trigger the build to get it staged again.

[kennknowles]

This is so good.

[asfbot]

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Jenkins built the site at commit id f7c0341 with Jekyll and staged it here. Happy reviewing.

Note that any previous site has been deleted. This staged site will be automatically deleted after its TTL expires. Push any commit to the pull request branch or re-trigger the build to get it staged again.

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