docs: add CSV Loading Guide Word document

[amar-python]

Summary

• Adds CSV_Loading_Guide.docx — a beginner-friendly, step-by-step Word document explaining how to load any CSV file into PostgreDataMigrationApp
• Covers: what a CSV is, prerequisites, one-time setup, loading files, querying data, quick reference table, and troubleshooting
• Written so someone with no prior experience can follow it end-to-end

Test plan

• Open CSV_Loading_Guide.docx in Microsoft Word and verify formatting
• Verify all commands in the guide match Makefile and csv_utilise.sh usage
• Confirm no regressions to existing files