Feat/add read more link as properties

[karlbaumhauer]

Fixes

• Fixes #

Proposed Changes

• Change

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[what-the-diff]

• Added an optional target link to the shave function.
• Updated README with new options and examples for using a target link in Shave.
• Fixed some linting errors that were introduced by adding the new code (mostly missing semicolons).
• Added a new option to the shave function called targetLink.
• The target link is an object that contains text, url and tabindex properties for creating a read more link at the end of truncated content.
• If no options are passed in then it will default to empty string values so as not break existing functionality or code using this library already (backwards compatibility).
• I have also added some tests around these changes which can be found in /tests/test-readmorelinkoptions folder within my fork on github: https://github.com/jamesdixon92/shave