Fix examples and add coverage badge

[shivammathur]

• Fix Laravel with postgresql example
• Add coverage badge
• Rename directory example -> examples

[codecov]

Codecov Report

Merging #51 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master    #51   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           2      2           
  Lines         171    171           
=====================================
  Hits          171    171

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