Use basic BearSSL ciphers on low memory boards (#1810)

* Use basic BearSSL ciphers on low memory boards

* Move BearSSL basic flag to recommendation

code/platformio.ini

@@ -52,6 +52,14 @@ debug_flags = -DDEBUG_ESP_CORE -DDEBUG_ESP_SSL -DDEBUG_ESP_WIFI -DDEBUG_ESP_HTTP
 #    -DPIO_FRAMEWORK_ARDUINO_LWIP_HIGHER_BANDWIDTH  = v1.4 Higher Bandwidth (default)
 #    -DPIO_FRAMEWORK_ARDUINO_LWIP2_LOW_MEMORY       = v2 Lower Memory
 #    -DPIO_FRAMEWORK_ARDUINO_LWIP2_HIGHER_BANDWIDTH = v2 Higher Bandwidth
+#
+# BearSSL ciphers:
+#   When building on core >= 2.5, you can add the build flag -DBEARSSL_SSL_BASIC in order to build BearSSL with a limited set of ciphers:
+#     TLS_RSA_WITH_AES_128_CBC_SHA256 / AES128-SHA256
+#     TLS_RSA_WITH_AES_256_CBC_SHA256 / AES256-SHA256
+#     TLS_RSA_WITH_AES_128_CBC_SHA / AES128-SHA
+#     TLS_RSA_WITH_AES_256_CBC_SHA / AES256-SHA
+#  This reduces the OTA size with ~45KB, so it's especially useful on low memory boards (512k/1m).
 # ------------------------------------------------------------------------------
 board_1m = esp01_1m
 board_2m = esp_wroom_02