docs: add example for parsing date columns with readr::read_csv()

[tanmaydimriGSOC]

Summary

Adds a concise README example demonstrating how to parse date columns when importing CSVs with readr::read_csv(). The snippet shows two approaches:

• specifying col_types with col_date() when formats are consistent
• reading as character and using parse_date() for mixed or locale-specific formats

Files changed

• README.md (example added under Usage)

Why

This addresses a common usability question (date parsing) and helps users avoid subtle errors when reading CSV files.

How to test

1. Copy the example into an R session.
2. Verify df$date and df2$date_parsed are parsed correctly.

Checklist

• Documentation only
• Example runs locally
• No API changes

[tanmaydimriGSOC]

Tested locally, happy to adjust if needed”