docs: Add section for server verification (esp_https_ota)

- Updated OTA example README

docs/en/api-reference/protocols/esp_tls.rst

@@ -40,6 +40,8 @@ The ESP-TLS  component has a file :component_file:`esp-tls/esp_tls.h` which cont
 of the two SSL/TLS Libraries between mbedtls and wolfssl for its operation. API specific to mbedtls are present in :component_file:`esp-tls/private_include/esp_tls_mbedtls.h` and API
 specific to wolfssl are present in :component_file:`esp-tls/private_include/esp_tls_wolfssl.h`.
 
+.. _esp_tls_server_verification:
+
 TLS Server verification
 -----------------------
 

docs/en/api-reference/system/esp_https_ota.rst

@@ -32,6 +32,14 @@ Application Example
             return ESP_OK;
         }
 
+
+Server Verification
+-------------------
+
+Please refer to :ref:`ESP-TLS: TLS Server Verification <esp_tls_server_verification>` for more information on server verification. The root certificate (in PEM format) needs to be provided to the :cpp:member:`esp_http_client_config_t::cert_pem` member.
+
+.. note:: The server-endpoint **root** certificate should be used for verification instead of any intermediate ones from the certificate chain. The reason being that the root certificate has the maximum validity and usually remains the same for a long period of time. Users can also use the ``ESP x509 Certificate Bundle`` feature for verification, which covers most of the trusted root certificates (using the :cpp:member:`esp_http_client_config_t::crt_bundle_attach` member).
+
 Partial Image Download over HTTPS
 ---------------------------------