[ADD] sign: add aadhar esign documentation

Author: nikj-odoo

content/applications/productivity/sign.rst

@@ -276,6 +276,46 @@ Upon signing the document, the signer completes the :guilabel:`Signature` field
 clicking on :guilabel:`Validate & Send Completed Document`, triggering a
 :guilabel:`Final verification` page where authentication via itsme® is required.
 
+.. _sign/Aadhaar:
+
+Aadhaar eSign
+~~~~~~~~~~~~~
+
+Aadhaar eSign allows signers in India to digitally sign documents using their Aadhaar number
+and OTP verification. This provides a **secure and legally valid** way to complete signatures
+directly within Odoo Sign.
+
+You can enable feature Aadhar sign from the **sign configuration.**
+
+.. image:: sign/aadhar-configration.png
+   :alt: install Aadhaar eSign
+
+:guilabel:`Configure Aadhaar eSign for a Signer`
+
+Upload the document that needs to be signed. Add a signer by clicking **Add** in the
+**Signers** section.In the **Signer Edition** dialog (see image below), select
+**Aadhaar eSign** in the **Authentication** field. Once done, add the **Signature**
+field and send the document to the signer.
+
+.. image:: sign/aadhar-identification.png
+   :alt: select customer identified with Aadhaar eSign
+
+:guilabel:`Sign with Aadhaar eSign`
+
+As the signer, complete the signature and click on the Validate button. You will be
+redirected to the eMudhra portal (government-certified authority), where Signers must
+enter their **Aadhaar number** and authenticate themselves with a **one-time password (OTP)**
+sent to the phone number associated with their Aadhaar number.
+
+.. image:: sign/aadhar-otp-verification.png
+   :alt: Aadhaar OTP verification
+
+After entering the OTP, signers can complete the e-signing process and finalize the document.
+
+In the downloaded document, users will see the **attached certification** from eMudhra.
+This certification serves as a **legally valid proof**, issued by a government-authorized
+eSign provider, confirming that the document was signed by the correct Aadhaar holder.
+
 Signatory hash
 ==============