[HTTP Binding]: adding metadata options for client auth during mTLS (#3050)

* [HTTP Binding]: adding metadata options for client authentication during mTLS

Signed-off-by: Pravin Pushkar <ppushkar@microsoft.com>

* Apply suggestions from code review

Co-authored-by: Hannah Hunter <94493363+hhunter-ms@users.noreply.github.com>
Signed-off-by: Pravin Pushkar <ppushkar@microsoft.com>

* Update daprdocs/content/en/reference/components-reference/supported-bindings/http.md

Signed-off-by: Mark Fussell <markfussell@gmail.com>

* Update daprdocs/content/en/reference/components-reference/supported-bindings/http.md

Signed-off-by: Mark Fussell <markfussell@gmail.com>

* Update daprdocs/content/en/reference/components-reference/supported-bindings/http.md

Signed-off-by: Mark Fussell <markfussell@gmail.com>

---------

Signed-off-by: Pravin Pushkar <ppushkar@microsoft.com>
Signed-off-by: Mark Fussell <markfussell@gmail.com>
Co-authored-by: Hannah Hunter <94493363+hhunter-ms@users.noreply.github.com>
Co-authored-by: Mark Fussell <markfussell@gmail.com>

daprdocs/content/en/reference/components-reference/supported-bindings/http.md

@@ -20,6 +20,13 @@ spec:
   metadata:
   - name: url
     value: http://something.com
+  - name: MTLSRootCA
+    value: /Users/somepath/root.pem #<path to root CA> or <pem encoded string>
+  - name: MTLSClientCert
+    value: /Users/somepath/client.pem #<path to client cert> or <pem encoded string>
+  - name: MTLSClientKey
+    value: /Users/somepath/client.key #<path to client key> or <pem encoded string>
+
 ```
 
 ## Spec metadata fields
@@ -27,6 +34,9 @@ spec:
 | Field              | Required | Binding support | Details | Example |
 |--------------------|:--------:|--------|--------|---------|
 | url                | Y        | Output |The base URL of the HTTP endpoint to invoke | `http://host:port/path`, `http://myservice:8000/customers`
+| MTLSRootCA         | N        | Output |Path to root ca certificate or pem encoded string |
+| MTLSClientCert     | N        | Output |Path to client certificate or pem encoded string  |
+| MTLSClientKey      | N        | Output |Path client private key or pem encoded string |
 
 ## Binding support
 
@@ -292,6 +302,17 @@ curl -d '{ "operation": "get" }' \
 
 {{< /tabs >}}
 
+## Using mTLS or enabling client TLS authentication along with HTTPS
+You can configure the HTTP binding to use mTLS or client TLS authentication along with HTTPS by providing the `MTLSRootCA`, `MTLSClientCert`, and `MTLSClientKey` metadata fields in the binding component.
+
+These fields can be passed as a file path or as a pem encoded string. 
+- If the file path is provided, the file is read and the contents are used. 
+- If the pem encoded string is provided, the string is used as is.
+When these fields are configured, the Dapr sidecar uses the provided certificate to authenticate itself with the server during the TLS handshake process.
+
+### When to use:
+You can use this when the server with which the HTTP binding is configured to communicate requires mTLS or client TLS authentication.
+
 
 ## Related links