docs: add output_dir="." to all save_annotated_documents examples

[aksg87]

Summary

This PR ensures consistent file saving behavior across all documentation examples by adding output_dir="." to all save_annotated_documents calls.

Problem

Without explicitly setting output_dir, files are saved to test_output/ by default, which can confuse users who expect files to be saved in their current directory.

Solution

Added output_dir="." parameter to all save_annotated_documents calls in:

• README.md
• docs/examples/longer_text_example.md
• docs/examples/medication_examples.md (first occurrence)

This follows the same pattern that was applied to one instance in medication_examples.md previously.

Testing

All examples have been verified to include the parameter. Users will now find their output files in their current working directory as expected.