Place MBEDTLS_CONFIG_FILE and such into a new section

Include this new section in the "full for documentation" (`realfull`)
configuration, so that these options are documented in the official
documentation build (`scripts/apidoc_full.sh`).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/scripts/config.py b/scripts/config.py
index ded7785..19b60e1 100755
--- a/scripts/config.py
+++ b/scripts/config.py
@@ -152,8 +152,16 @@
     return section.endswith('support') or section.endswith('modules')
 
 def realfull_adapter(_name, active, section):
-    """Activate all symbols found in the system and feature sections."""
-    if not is_full_section(section):
+    """Activate all symbols found in the global and boolean feature sections.
+
+    This is intended for building the documentation, including the
+    documentation of settings that are activated by defining an optional
+    preprocessor macro.
+
+    Do not activate definitions in the section containing symbols that are
+    supposed to be defined and documented in their own module.
+    """
+    if section == 'Module configuration options':
         return active
     return True