docs: update document for enveloping proof flow (#133)

* docs: update document for enveloping proof flow

* refactor: change sidebar position number

* docs: refactor some sentences in verifiable credentials

* Update verifiable-credentials.md

* Update description on verifiable-credentials.md

documentation/docs/mock-apps/common/verifiable-credentials.md

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+---
+sidebar_position: 46
+title: Verifiable Credentials
+---
+
+import Disclaimer from '../../\_disclaimer.mdx';
+
+<Disclaimer />
+
+## Description
+
+Verifiable Credentials follow the flow of the W3C Verifiable Credentials Data Model 2.0. It is a standard for issuing, presenting, and verifying credentials in a secure and privacy-preserving manner. Verifiable Credentials are tamper-proof, cryptographically signed documents containing claims about a subject, such as a person, organization, or device. They are issued by trusted entities known as issuers and can be presented to verifiers to prove the authenticity of the claims.
+
+---
+Please take a look at the [Verifiable Credentials Data Model 2.0](https://www.w3.org/TR/vc-data-model-2.0/) for more information on the specification
+
+## Credential Securing Mechanism
+
+Verifiable Credentials rely on digital signatures or proofs to ensure the authenticity and integrity of the issued credentials. Two key securing mechanisms are used:
+
+1. **Embedded Proofs**: The proof is included directly within the credential object, typically using JSON Web Signatures (JWS) or JSON-LD Signatures.
+2. **Enveloping Proofs**: The proof wraps the entire credential as a container, using formats like:
+   - **JOSE**: JSON Object Signing and Encryption, which enables signed credentials using JWS.
+   - **COSE**: CBOR Object Signing and Encryption, used for compact and efficient serialization.
+
+Credentials can also be encrypted if sensitive information needs to be protected. Encryption keys are managed through secure Key Management Systems (KMS) to ensure credentials remain confidential and tamper-proof.
+
+---
+
+Refer to the [Verifiable Credentials Data Model 2.0 - Securing Mechanisms](https://www.w3.org/TR/vc-data-model-2.0/#securing-mechanisms) for more information on the specification.
+
+## Credential Payload Structure
+
+When issuing, the credential will follow the [Verifiable Credentials API v0.3 - Issue Credential](https://w3c-ccg.github.io/vc-api/#issue-credential) specification. A typical payload contains the following fields:
+
+Example: EnvelopedVerifiableCredential
+
+```json
+{
+  "@context": ["https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2"],
+  "type": "EnvelopedVerifiableCredential",
+  "id": "data:application/vc-ld+jwt,eyJhbGciOiJFZERTQSIsImlzcyI6ImRpZDp3ZWI6ZGRiYy0xMTYtMTA2LTE..."
+}
+```
+
+Example: JSON-LD Verifiable Credential with a Proof
+
+```json
+{
+  "@context": ["https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2"],
+  "id": "http://example.edu/credentials/1872",
+  "type": ["VerifiableCredential", "AlumniCredential"],
+  "issuer": "https://example.edu/issuers/14",
+  "issuanceDate": "2023-03-21T19:23:24Z",
+  "credentialSubject": {
+    "id": "did:example:abcd1234",
+    "alumniOf": "Example University"
+  },
+  "proof": {
+    "type": "Ed25519Signature2020",
+    "created": "2023-03-21T19:23:24Z",
+    "proofPurpose": "assertionMethod",
+    "verificationMethod": "https://example.edu/issuers/14#key-1",
+    "jws": "eyJhbGciOiJFZERTQSJ9..b9W5k8..."
+  }
+}
+```
+
+---
+
+When verifying a credential, the verifier will call the server to verify the credential. The server will return the verification result as follows:
+
+```json
+{
+  "verified": true,
+  ...
+}
+```
+
+---
+
+Refer to the [Verifiable Credentials API v0.3 - Verify Credential](https://w3c-ccg.github.io/vc-api/#verify-credential) for more information on the specification.