add tool description in help

[tarunKoyalwar]

pdtm version:

v0.0.2

Current Behavior:

• pdtm help (i.e pdtm -h) is missing tool description

$ pdtm -h


Usage:
  pdtm [flags]
...

Expected Behavior:

Example

$ katana -h
Katana is a fast crawler focused on execution in automation
pipelines offering both headless and non-headless crawling.

Usage:
  katana [flags]
...

Steps To Reproduce:

Anything else: