Document parser package helper functions in main README

[Copilot]

PR #47 added parser package with Parse() and ToAddressRequest() helper functions but didn't update the main README. These functions handle free-form address parsing and will be frequently used.

Changes

Main README (README.md)

• Added comprehensive table of contents with 11 main sections and 30+ subsections for easy navigation
• Added "Address Parsing" section positioned before "Advanced Usage" (higher hierarchy than advanced topics)
• Includes quick example, USPS API integration pattern, and common use cases
• Links to detailed parser package README for comprehensive documentation

Godoc Enhancements (parser/parser.go, parser/types.go)

• Enhanced Parse() to explain tokenization, standardization, and validation steps
• Enhanced ToAddressRequest() to describe component combination into USPS API format

Example Usage

// Parse free-form address input
input := "123 North Main Street Apt 4B, New York, NY 10001-1234"
parsed, diagnostics := parser.Parse(input)

// Check for errors
for _, d := range diagnostics {
    if d.Severity == parser.SeverityError {
        return fmt.Errorf("parse error: %s", d.Message)
    }
}

// Convert to AddressRequest and validate with USPS
req := parsed.ToAddressRequest()
resp, err := client.GetAddress(ctx, req)

• Fixes Document New Helper Functions #48

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Document New Helper Functions</issue_title>
<issue_description>New functions were added in this PR: https://github.com/my-eq/go-usps/pull/47/files

The README was not updated to describe and demonstrate these functions.
Double check their own comments are sufficient for developers and godoc

These helper functions will be used frequently and should be higher in the README hierarchy than other advanced topics.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Document New Helper Functions #48

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[kmesiab]

@copilot add a table of contents

[Copilot]

@copilot add a table of contents

Added comprehensive table of contents with 11 main sections and 30+ subsections. The TOC is positioned right after the badges and includes all major sections including the newly documented Address Parsing section. All links use GitHub-compatible anchor format for easy navigation. (de493b5)

[Copilot]

Pull Request Overview

This PR enhances documentation for the parser package and adds comprehensive navigation to the README. The changes improve developer experience by adding detailed inline documentation for parser functions and creating a structured table of contents for easier navigation of the extensive README.

• Enhanced godoc comments for parser functions with detailed descriptions of their behavior
• Added a comprehensive table of contents to README.md for easier navigation
• Added a new "Address Parsing" section in the README with usage examples and integration patterns

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
parser/types.go	Enhanced godoc for ToAddressRequest method to explain component combining logic
parser/parser.go	Enhanced godoc for Parse function to describe tokenization, validation, and diagnostic flow
README.md	Added table of contents and comprehensive "Address Parsing" section with examples