Clarify that EXCLUDE_FROM_FULL has exceptions from is_seamless_alt

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/scripts/config.py b/scripts/config.py
index bc9a514..ecf95d1 100755
--- a/scripts/config.py
+++ b/scripts/config.py
@@ -210,6 +210,9 @@
 
     Exclude alternative implementations of library functions since they require
     an implementation of the relevant functions and an xxx_alt.h header.
+
+    If a symbol matches this naming pattern but doesn't behave like the others,
+    list it in EXCLUDE_FROM_FULL.
     """
     return name.startswith('MBEDTLS_PLATFORM_')