Add documentation for mc put `--storage-class

[molivier]

Adding documentation for additional parameter of mc put subcommand. fix #1481

[djwfyi]

Thanks for the PR!
We're going to hold this a bit as we're in the midst of moving docs to a new location and doing some other reworking with them.

[ravindk89]

This might break a lot, but @molivier if you can try to set the target as the singleplat branch instead that might help.

[molivier]

Thank you for your responses. I will switch to the branch recommended by @ravindk89.