Fixed `esp_tls_conn_write` documentation.
Fixed `esp_tls_conn_write` documentation.

Return value `0` in actual is case of partial write and not error as per `mbedtls_ssl_write`
Modified documentation of `esp_tls_conn_write` accordingly.

Even `esp_wolfssl_write` API considers just negative returns as errors.

Signed-off-by: Vikram Dattu <a2cfbbb20d5d65b8337688f1322301a577415db0@espressif.com>

espressif/esp-idf,espressif/esp-idf,espressif/esp-idf,espressif/esp-idf