ScaleIO volume migration documentation (#321)

* Update service offering section with new compute offering and disk offering changes (#238)

* Added sample ssh commands to connect to Control and Worker node (#304)

Co-authored-by: dahn <daan.hoogland@gmail.com>
Co-authored-by: Abhishek Kumar <abhishek.mrt22@gmail.com>

* Trivial editing (#305)

* volume migration docs for PowerFlex/ScaleIO storage pool

* Rename VM to Instance

* Update storage.rst package update limitation

* revert changes, as it's not needed storage.rst

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Co-authored-by: kiranchavala <kiranchavala@gmail.com>
Co-authored-by: dahn <daan.hoogland@gmail.com>
Co-authored-by: Abhishek Kumar <abhishek.mrt22@gmail.com>
Co-authored-by: Brad Hards <bradh@frogmouth.net>
Co-authored-by: Boris Stoyanov - a.k.a Bobby <bss.stoyanov@gmail.com>
2 files changed