experimental[patch]: update module doc strings (#19539)

Added missed module descriptions. Fixed format.

libs/experimental/langchain_experimental/data_anonymizer/__init__.py

@@ -1,4 +1,13 @@
-"""Data anonymizer package"""
+"""**Data anonymizer** contains both Anonymizers and Deanonymizers.
+It uses the [Microsoft Presidio](https://microsoft.github.io/presidio/) library.
+
+**Anonymizers** are used to replace a `Personally Identifiable Information (PII)`
+entity text with some other
+value by applying a certain operator (e.g. replace, mask, redact, encrypt).
+
+**Deanonymizers** are used to revert the anonymization operation
+(e.g. to decrypt an encrypted text).
+"""
 from langchain_experimental.data_anonymizer.presidio import (
     PresidioAnonymizer,
     PresidioReversibleAnonymizer,