[Smart Hashing] Add smart hashing documentation in readme

[harsh-joshi99]

Adds documentation about the new smart hashing module.

Testing

N/R: Documentation changes only.

Include any additional information about the testing you have completed to
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any of the tasks you completed below during your testing.

• Added unit tests for new functionality
• Tested end-to-end using the local server
• [If destination is already live] Tested for backward compatibility of destination. Note: New required fields are a breaking change.
• [Segmenters] Tested in the staging environment
• [Segmenters] [If applicable for this change] Tested for regression with Hadron.

[varadarajan-tw]

This section is not needed.

Suggested change

	### Key Benefits
	- **Automatic Hashing Detection**: Avoids double-hashing by identifying already hashed values.
	- **Consistent Hashing**: Applies the correct algorithm and format across use cases.
	- **Optional Input Normalization**: Supports custom logic for cleaning and standardizing inputs (e.g., trimming, formatting).

[varadarajan-tw]

Suggested change

	Use the `processHashing` utility to hash Personally Identifiable Information (PII)—like email addresses and phone numbers.
	This utility simplifies workflows by automatically detecting and handling pre-hashed values, ensuring compatibility across destinations and preventing common data-matching issues.
	Our popular segment Adtect destinations support [automatic hash detection](https://segment.com/docs/connections/destinations/#hashing) of personally identifyable information (PII). If your destination hashes PII data, we recommend you use the `processHashing` utility instead of `createHash` from `crypto` module.
	The `processHashing` utility supports `md5`, `sha1`,`sha224`,`sha256`,`sha384` and`sha512` hashing algorithms. It can output digests in `hex` or `base64` format.
	**Note**: For empty or whitespace-only strings, the `processHashing` outputs an empty string instead of throwing an error like `createHash` hash module.

[varadarajan-tw]

Suggested change

	```
	```

[varadarajan-tw]

Suggested change

	### Notes
	**Empty Input Handling**: Returns `''` for empty or whitespace-only strings.
	**Supported Hash Algorithms**
	- `md5`
	- `sha1`
	- `sha224`
	- `sha256`
	- `sha384`
	- `sha512`
	All algorithms support `hex` and `base64` digest formats.
	**Requesting Additional Algorithms**
	To request additional hash algorithms, contact [email protected].
	### Notes
	**Empty Input Handling**: Returns `''` for empty or whitespace-only strings.
	**Supported Hash Algorithms**
	- `md5`
	- `sha1`
	- `sha224`
	- `sha256`
	- `sha384`
	- `sha512`
	All algorithms support `hex` and `base64` digest formats.
	**Requesting Additional Algorithms**
	To request additional hash algorithms, contact [email protected].

[joe-ayoub-segment]

I wonder should we explicitly say that this feature will detect if a string is already hashed, and will only apply a hash if the string is not already hashed?