Merge conflicts between solutions for issue-19 & issue-20

[a-parris21]

Resolved the conflicts when merging issue-19 and issue-20 branches into main branch: https://github.com/a-parris21/ap21-ssg/commit/d150685

However, I accepted the merge for the mainOutputDir() function from the wrong branch so I adjusted the code to resolve this. Only changes made were:

• added the outputDir parameter to the mainOutputDir() function
• replaced references to the default file path with outputDir so that mainOutputDir() function would use its parameter instead of the default file path

Issue closed by: https://github.com/a-parris21/ap21-ssg/commit/c1359b4