fix: improve network warning message clarity

Reword the INTERNET NOT REACHABLE warning to explain that SDKMAN!
needs an active connection, and that the healthcheck config is for
users whose connection is active but slow — not a fix for no internet.

Author: Chloé

src/main/bash/sdkman-availability.sh

@@ -47,8 +47,10 @@ function __sdkman_display_network_warning() {
 	if [[ -z "$healthcheck_status" ]]; then
 		__sdkman_echo_red "==== INTERNET NOT REACHABLE! ==================================================="
 		__sdkman_echo_red ""
-		__sdkman_echo_red " Some functionality is disabled or only partially available."
-		__sdkman_echo_red " If this persists, disable the healthcheck in ${SDKMAN_DIR}/etc/config:"
+		__sdkman_echo_red " SDKMAN! needs an active internet connection for full functionality."
+		__sdkman_echo_red ""
+		__sdkman_echo_red " If your connection is active but slow, you can disable the startup"
+		__sdkman_echo_red " healthcheck in ${SDKMAN_DIR}/etc/config:"
 		__sdkman_echo_red ""
 		__sdkman_echo_red "   sdkman_healthcheck_enable=false"
 		__sdkman_echo_red ""