Allow up to 500mW transmission power for EU868 region

The European Union regulations clearly state that the power limit for this frequency range is 500 mW, or 27 dBm. goTenna Mesh uses the same frequency range and power limit too.

It also states that we can use interference avoidance and spectrum access techniques to avoid a duty cycle.

It might be worthwhile in the future to implement frequency hopping to avoid duty cycling.

(Please refer to page 69 in the following document)
        https://ec.europa.eu/growth/tools-databases/tris/index.cfm/ro/search/?trisaction=search.detail&year=2021&num=528&dLang=EN

src/mesh/RadioInterface.cpp

@@ -35,8 +35,16 @@ const RegionInfo regions[] = {
         https://www.legislation.gov.uk/uksi/1999/930/schedule/6/part/III/made/data.xht?view=snippet&wrap=true
 
         audio_permitted = false per regulation
+
+        Special Note:
+        The link above describes LoRaWAN's band plan, stating a power limit of 16 dBm. This is their own suggested specification,
+        we do not need to follow it. The European Union regulations clearly state that the power limit for this frequency range is 500 mW, or 27 dBm.
+        It also states that we can use interference avoidance and spectrum access techniques to avoid a duty cycle.
+        It might be worthwhile in the future to implement frequency hopping to avoid duty cycling.
+        (Please refer to page 69 in the following document)
+        https://ec.europa.eu/growth/tools-databases/tris/index.cfm/ro/search/?trisaction=search.detail&year=2021&num=528&dLang=EN
      */
-    RDEF(EU868, 869.4f, 869.65f, 10, 0, 16, false, false),
+    RDEF(EU868, 869.4f, 869.65f, 10, 0, 27, false, false),
 
     /*
         https://lora-alliance.org/wp-content/uploads/2020/11/lorawan_regional_parameters_v1.0.3reva_0.pdf