Moderation info overhaul

The [moderation page](https://docs.chocolatey.org/en-us/community-repository/moderation/) has a couple of places that could use some work.

- The [becoming a reviewer](https://docs.chocolatey.org/en-us/community-repository/moderation/#becoming-a-reviewer) section still has is TBD.
- The [moderator review](https://docs.chocolatey.org/en-us/community-repository/moderation/#moderator-review) section has a note from 2015 about moderators not needing to check for duplicate packages. Is that note still valid?
- The [guidelines](https://docs.chocolatey.org/en-us/community-repository/moderation/#guidelines) section has guidelines about including a #trial tag for trial software and a #license tag for software that needs a license. It says that they became requirements in Feb 2016. Is that correct? Should they be moved to the requirements section? If they are requirements, it might be a good idea to remind the moderators of the requirement because I had a package for trial software reviewed, and no comment was made that I should include a trial tag. [See review comments](https://chocolatey.org/packages/advanced-installer/16.7)
- The [moderator process](https://docs.chocolatey.org/en-us/community-repository/moderation/#guidelines) section has a number of images that are from the old site layout. They should be evaluated if they need to be updated.
- Add the guidance that packages should not have tags of competing products. [Reference](https://github.com/bcurran3/ChocolateyPackages/issues/10)

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This is more adding than fixing, but adding guidance on touching `$env:ChocolateyInstall`.

Where and what are packages permitted to do in `$env:ChocolateyInstall`?
- Are they ever allowed to change any permissions anywhere? Probably no?
- Are they allowed to use the tools inside `$env:ChocolateyInstall\tools` directly? Probably no also, but I don't think this restriction is documented.
- Are they allowed to check what packages are installed in `$env:ChocolateyInstall\lib`? No, [via @mkevenaar on gitter](https://gitter.im/chocolatey/choco?at=5fd8d7217beb2f6e63b33aaf), but again, the restriction is not documented.
- Are they allowed to directly manipulate the files in `$env:ChocolateyInstall\bin`? Reference [gsudo install script](https://chocolatey.org/packages/gsudo#files)