Doc improvement. Add quotes around whisper hash in docs since it contains `|` symbol which can cause problems.

[ritwik-g]

https://docs.unstract.com/unstract/unstract_platform/cli/unstract_cli/#extract-text-with-llmwhisperer

When following the nowait example from public doc it is easy to miss quotes around whisper hash. Since the whisper hash always contains the | character in it this can confuse the terminal with PIPE causing issues