Add npm-shrinkwrap.json usage

[drazisil]

Description

• Add usage example for npm-shrinkwrap.json
• Add note about no output === success

Types of changes

• Docs clarification (non-breaking change which improves usibility)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Related Issue

None

Motivation and Context

Prevents users from hitting this error:

ABORTING lockfile lint process due to error exceptions 

Unable to find relevant lockfile parser for "npm-shrinkwrap.json", consider passing the --type option. 

Error
    at new ParsingError (/home/drazisil/.npm/_npx/12990/lib/node_modules/lockfile-lint/node_modules/lockfile-lint-api/src/common/ParsingError.js:27:33)
    at ParseLockfile.parseSync (/home/drazisil/.npm/_npx/12990/lib/node_modules/lockfile-lint/node_modules/lockfile-lint-api/src/ParseLockfile.js:53:13)
    at ValidateHostManager (/home/drazisil/.npm/_npx/12990/lib/node_modules/lockfile-lint/src/validators/index.js:40:27)
    at validators.forEach.validator (/home/drazisil/.npm/_npx/12990/lib/node_modules/lockfile-lint/src/main.js:35:28)
    at Array.forEach (<anonymous>)
    at Object.runValidators (/home/drazisil/.npm/_npx/12990/lib/node_modules/lockfile-lint/src/main.js:25:14)
    at Object.<anonymous> (/home/drazisil/.npm/_npx/12990/lib/node_modules/lockfile-lint/bin/lockfile-lint.js:31:17)
    at Module._compile (internal/modules/cjs/loader.js:778:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32) 

error: command failed with exit code 1 

How Has This Been Tested?

Confirmed the error does not occur when passing the --type flag

Screenshots (if appropriate):

Checklist:

• [ x] I have updated the documentation (if required).
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• [x ] All new and existing tests passed.
• [x ] I added a picture of a cute animal cause it's fun

Photo Credit: https://unsplash.com/photos/YyEotvsoOXs

[codecov-io]

Codecov Report

Merging #73 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #73   +/-   ##
=======================================
  Coverage   95.08%   95.08%           
=======================================
  Files          11       11           
  Lines         183      183           
  Branches       29       29           
=======================================
  Hits          174      174           
  Misses          8        8           
  Partials        1        1

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[lirantal]

Thanks a bunch @drazisil ❤️
Minor typo correction and we'll land this in

[drazisil]

Minor typo correction and we'll land this in

What typo correction?

[lirantal]

What typo correction?

Silly me. Forgot to submit the review. See now.