Update cbstats warmup content with bucket data

[rao-shwe]

DOC-13324

Preview doc page for 8.0 version - warmup:

• Removed raw from the command cbstats [host]:[dataport] -b [bucket_name] -p [bucket_password] raw warmup.
• Updated the description of ep_warmup_estimate_time in the table:
  • from "Thne estimated time in microseconds to do warmup."
  • to "The time taken, measured in milliseconds, to discover the estimated number of keys that may be warmed up."
• Corrected ep_warmup_keys_count.
  • Removed s from keys.
• Removed the instances of ep_warmup_min_items_threshold and ep_warmup_min_memory_threshold from the table and code example.
• Tested in the 8.0 environment. Added data into the travel-sample bucket, and generated the correct code example request and response.

Preview docs site login credentials.

Ignore the preview yml file.