feat: XLSX - CSV (#48)
* build(gomod): add tealeg/xlsx as dep
* feat(documents): add a csv struct that converts csv to xlsx files
* test(document): add test function to test csv-xlsx
* feat(xlsx): add a xlsx struct able to convert xlsx files to csv ones
* test(documents): add a test function to make sure xlsx - csv works as expected
* feat(documents): add changes to integrate the new kind of documents
* refactor(csv): remove the outdir
* feat(main): add the text kind of document to the main file
* docs(readme): add the csv and xlsx kind of documents to the conversion matrix
* build(gomod): resolve conflicts on go module
