Add Specs

[Reion19]

##All Submissions:

[ ✅ ] Have you followed the guidelines in our Contributing document?
[ ✅ ] Have you checked to ensure there aren't other open Pull Requests for the same update/change?
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Summary of Changes

This PR includes 2 commits focused on testing and documentation.
Key Updates:

Added RSpec tests
Covered most common use cases of the gem to improve reliability and prevent regressions.

Updated README
Minor adjustments and clarifications to the usage instructions.

Nothing fancy — mostly specs and docs.