docs(ssl): update comments for TLS/SSL certificate management in ESP8266

Author: tyeth

src/AdafruitIO_Definitions.h

@@ -115,7 +115,7 @@ class AdafruitIOGroupCallback {
 #define AIO_ERROR_TOPIC "/errors"      ///< Adafruit IO Error MQTT Topic
 #define AIO_THROTTLE_TOPIC "/throttle" ///< Adafruit IO Throttle MQTT Topic
 
-/* NB: io.adafruit.com TLS/SSL certificate changes every 6months, and pinning
+/* NOTE: io.adafruit.com TLS/SSL certificate changes every 6months, and pinning
 certificates is no longer recommended. Migrate to a larger MCU like ESP32
 which can accomodate root certificates and verify chains of trust.  */
 /* For older devices like ESP8266 you can generate the latest fingerprint with:

src/wifi/AdafruitIO_ESP8266.h

@@ -25,7 +25,7 @@
 /* NOTE - Projects that require "Secure MQTT" (TLS/SSL) also require a new
  * SSL certificate every year. If adding Secure MQTT to your ESP8266 project is
  * important  - please switch to using the modern ESP32 (and related models)
- * instead of the ESP8266 to avoid updating the SSL fingerprint every 6months.
+ * instead of the ESP8266 to avoid updating the SSL fingerprint every 6 months.
  *
  * If you've read through this and still want to use "Secure MQTT" with your
  * ESP8266 project, we've left the "WiFiClientSecure" lines commented out. To