docs(input[range]): Fix erroneous examples

[jfreyre]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

Documentation update.

What is the current behavior? (You can also link to an open issue here)

Examples of input[range] doesn't works well because it use only the scope.min value instead of scope.max

What is the new behavior (if this is a feature change)?

• When updating min value, it update the min only.
• When updating max value, it update the max only.

Does this PR introduce a breaking change?

No.

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/angular/angular.js/blob/master/CONTRIBUTING.md#commit-message-format
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:

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[jfreyre]

I signed it! ;)

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