Updated spec.md with few rewordings.

[ashish-billore]

Updated few lines to make the meaning more explicit.

[ashish-billore]

Thanks @jdef for review and approval.
If these changes look good, could this PR be merged?
Thanks!

[saad-ali]

/lgtm
/approve

@ashish-billore can you please sign the CLA: https://github.com/container-storage-interface/spec/blob/master/CONTRIBUTING.md#licence-and-cla

[ashish-billore]

Thanks @saad-ali for review.
The email link (https://github.com/container-storage-interface/spec/blob/master/[email protected]) in above CLA document seems to be broken.

Also, the CLA doc above is a pdf form, so does it need to be printed, filled/signed and scanned to be sent to [email protected]?
Is there an alternate, online way to sign the CLA?

[saad-ali]

@ashish-billore unfortunately it's a manual process right now. You'd have to print sign and email the CLA to [email protected]