Workspace documentation refer to deprecated modes of operation

This issue has been migrated from https://github.com/deeplearning4j/deeplearning4j/issues/6198

Original author @DrChainsaw

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Hi,

I just happened to see that the documentation for workspaces in the link below describes the now deprecated modes SEPARATE and SINGLE. From what I understand, the only supported modes now is ENABLED (more or less same as SEPARATE) and NONE.

https://deeplearning4j.org/docs/latest/deeplearning4j-config-workspaces

As a side note: SINGLE seemed to have almost 100% speedup over SEPARATE for architectures with many layers (e.g. inception or resnets) in some cases so the difference might have been more than "slight" in some cases. I posted some more info in #5288 in case this might be of interest to you.