apply copilot suggestion to update the comment

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Yijing Yan <yijingyan@microsoft.com>

Author: yijingyan2

rules/config

@@ -407,5 +407,5 @@ BUILD_SKIP_TEST ?= n
 # Default: disabled (no impact on clean builds without a warm cache)
 SONIC_CONFIG_USE_CCACHE ?= n
 
-# apt-get timeout for http connection
+# apt-get timeout for HTTP and HTTPS connections, in seconds
 BUILD_APT_GET_HTTP_TIMEOUT ?= 60