clarify client_sdk freeze in sentry_init()

Author: supervacuus

src/sentry_core.c

@@ -163,9 +163,9 @@ sentry_init(sentry_options_t *options)
     g_options = options;
 
     // *after* setting the global options, trigger a scope and consent flush,
-    // since at least crashpad needs that.
-    // the only way to get a reference to the scope is by locking it, the macro
-    // does all that at once, including invoking the backends scope flush hook
+    // since at least crashpad needs that. At this point we also freeze the
+    // `client_sdk` in the `scope` because some downstream SDKs want to override
+    // it at runtime via the options interface.
     SENTRY_WITH_SCOPE_MUT (scope) {
         if (options->sdk_name) {
             sentry_value_t sdk_name