Update cache.rst

The value for the `public` attribute should be specified without quotation marks. For the construction `public="false"`, actually `public` takes the value `true`, because a string converted to Boolean will always be `true`.
fixed typo
minor #296 Update cache.rst (marianflorin)

This PR was merged into the 3.0.x-dev branch.

Discussion
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Update cache.rst

The value for the `public` attribute should be specified without quotation marks. For the construction `public="false"`, actually `public` takes the value `true`, because a string converted to Boolean will always be `true`.

Commits
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e0c01a6 Update cache.rst