Bug Report

Describe the bug
Various updates needed to ensure the config parameters of gpu metrics input plugin are clear and concise.

To Reproduce
./fluent-bit -i gpu_metrics -h

Expected behavior
Expect clear and concise descriptions but existing descriptions are not informative.

Screenshots
N/A

Your Environment

• Version used: all
• Configuration: all
• Environment name and version (e.g. Kubernetes? What version?): all
• Server type and version: all
• Operating System and version: all
• Filters and plugins: in_gpu_metrics

Additional context
N/A