Fix usage of short forms for flags

[tetafro]

Before

$ ./talisman -h
Usage of ./talisman:
      --c string                 short form of checksum calculator
      --checksum string          checksum calculator calculates checksum and suggests .talsimarc format
      --d                        short form of debug
      --debug                    enable debug mode (warning: very verbose)
      --githook string           either pre-push or pre-commit (default "pre-push")
      --p string                 short form of pattern
      --pattern string           pattern (glob-like) of files to scan (ignores githooks)
      --rd string                short form of report directory
      --reportdirectory string   directory where the scan reports will be stored
      --s                        short form of scanner
      --scan                     scanner scans the git commit history for potential secrets
      --scanWithHtml             Generate html report. (**Make sure you have installed talisman_html_report to use this, as mentioned in Readme)**
      --swh                      short form of html report scanner
      --v                        short form of version
      --version                  show current version of talisman
pflag: help requested

After

$ ./talisman -h
Usage of ./talisman:
  -c, --checksum string          checksum calculator calculates checksum and suggests .talsimarc format
  -d, --debug                    enable debug mode (warning: very verbose)
  -g, --githook string           either pre-push or pre-commit (default "pre-push")
  -p, --pattern string           pattern (glob-like) of files to scan (ignores githooks)
  -r, --reportdirectory string   directory where the scan reports will be stored
  -s, --scan                     scanner scans the git commit history for potential secrets
  -w, --scanWithHtml             generate html report (**Make sure you have installed talisman_html_report to use this, as mentioned in Readme**)
  -v, --version                  show current version of talisman
pflag: help requested

[svishwanath-tw]

@tetafro Thanks for this. The clunky short form options hurt like a sore thumb.