docs: add README files for teepot-related crates

- Added comprehensive README files for the following new crates:
  - `teepot`
  - `teepot-tdx-attest-rs`
  - `teepot-tdx-attest-sys`
  - `teepot-tee-quote-verification-rs`
  - `teepot-vault`
- Each includes an overview, usage examples, installation instructions, and licensing details.

crates/teepot-vault/README.md

@@ -0,0 +1,134 @@
+# teepot-vault
+
+[![Crates.io](https://img.shields.io/crates/v/teepot-vault.svg)](https://crates.io/crates/teepot-vault)
+[![Documentation](https://docs.rs/teepot-vault/badge.svg)](https://docs.rs/teepot-vault)
+[![License](https://img.shields.io/crates/l/teepot-vault.svg)](LICENSE)
+
+A TEE (Trusted Execution Environment) secret manager that provides secure storage and retrieval of secrets for TEE applications, with a focus on Intel SGX enclaves.
+
+## Features
+
+- **Remote Attestation**: Verify Intel SGX enclaves and other TEEs using attestation reports
+- **Secure Communication**: Establish TLS connections with custom certificate verification based on TEE attestation
+- **HashiCorp Vault Integration**: Store and retrieve secrets with TEE-specific access controls
+- **Multi-signature Support**: PGP-based multi-signature verification for administrative commands
+- **Configurable TCB Levels**: Support for different Trusted Computing Base security levels
+
+## Installation
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+teepot-vault = "0.6.0"
+```
+
+## Usage
+
+### Creating a Vault Connection
+
+```rust
+use teepot_vault::client::{AttestationArgs, VaultConnection};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args = AttestationArgs {
+        sgx_mrsigner: Some("your_mrsigner_hex".to_string()),
+        sgx_mrenclave: Some("your_mrenclave_hex".to_string()),
+        server: "https://vault.example.com".to_string(),
+        sgx_allowed_tcb_levels: Some(vec!["Ok".to_string(), "ConfigNeeded".to_string()]),
+    };
+
+    let vault_conn = VaultConnection::new(&args, "my-tee-app".to_string()).await?;
+    
+    Ok(())
+}
+```
+
+### Storing and Retrieving Secrets
+
+```rust
+use serde::{Serialize, Deserialize};
+
+#[derive(Serialize, Deserialize)]
+struct MySecret {
+    api_key: String,
+    private_key: Vec<u8>,
+}
+
+// Store a secret
+let my_secret = MySecret {
+    api_key: "secret-key".to_string(),
+    private_key: vec![1, 2, 3, 4],
+};
+vault_conn.store_secret(my_secret, "secrets/my-app/config").await?;
+
+// Retrieve a secret
+let secret: MySecret = vault_conn.load_secret("secrets/my-app/config").await?.unwrap();
+```
+
+### Custom TEE Connections
+
+For more control over the connection and custom operations:
+
+```rust
+use teepot_vault::client::TeeConnection;
+
+let tee_conn = TeeConnection::new(&args);
+let client = tee_conn.client(); // Get the HTTP client for custom requests
+
+// Perform custom authenticated requests
+let response = client
+    .get("https://vault.example.com/custom/endpoint")
+    .send()
+    .await?;
+```
+
+## Server Components
+
+The crate also provides server-side utilities for building TEE-aware services:
+
+```rust
+use teepot_vault::server::{HttpResponseError, Status};
+use actix_web::{web, App, HttpServer, Result};
+
+async fn handler() -> Result<String, HttpResponseError> {
+    // Your TEE service logic here
+    Ok("Secure response".to_string())
+}
+
+#[actix_web::main]
+async fn main() -> std::io::Result<()> {
+    HttpServer::new(|| {
+        App::new()
+            .route("/api/secure", web::get().to(handler))
+    })
+    .bind("127.0.0.1:8080")?
+    .run()
+    .await
+}
+```
+
+## Requirements
+
+- Rust 1.70 or later
+- For SGX support: Intel SGX SDK and PSW (Platform Software)
+- HashiCorp Vault instance (for vault operations)
+- TEE environment (Intel SGX, Intel TDX, or compatible)
+
+## Security Considerations
+
+This crate is designed for use in high-security environments. When using it:
+
+1. Always verify attestation reports before trusting a TEE
+2. Use appropriate TCB levels for your security requirements
+3. Ensure proper key management for PGP signatures
+4. Follow HashiCorp Vault best practices for secret management
+
+## License
+
+This project is licensed under the Apache License 2.0 - see the LICENSE file for details.
+
+## Contributing
+
+Contributions are welcome! Please feel free to submit a Pull Request.