[Documentation:System] Add config include docs

_docs/instructor/assignment_configuration/configuration_path.md

@@ -39,6 +39,12 @@ previous uploads below.  The uploaded configurations are sequentially numbered b
 default, but the name may be edited by clicking on the pencil to the
 left of each configuration.
 
+For simple assignments, this upload may be a single `config.json` file.
+For more complex assignments, Submitty also supports C/C++ style
+comments and `#include` directives in `config.json`. If you use
+`#include`, upload a zip archive that contains `config.json` and the
+included files with their relative paths preserved.
+
 ![](/images/config_upload_interface.png)
 
 Note: These uploaded configurations are stored in the course directory:
@@ -55,6 +61,13 @@ However, repeatedly uploading files through this interface is a
 tedious workflow to develop and debug complex autograding
 configurations.
 
+For larger configurations, it is often easier to keep the files in a
+course repository and organize the autograding config across multiple
+files with `#include`. If a build error references a confusing line
+number, compare it against the generated / preprocessed config used
+during the build, including any generated config shown in the
+instructor build log.
+
 
 ### Course Autograding Configuration Directory
 
@@ -90,4 +103,4 @@ folders containing a file named 'config.json'.  Folders that are
 found will be displayed in the dropdown menu (prefixed by "DIRECTORY"), as well as warnings if 
 an error is encountered while searching the directory.
 
-![](/images/config_repo_box.png)
+![](/images/config_repo_box.png)

_docs/instructor/autograding/specification.md

@@ -10,7 +10,21 @@ redirect_from:
 
 You are allowed to have C/C++ style comments in a `config.json` file.
 These will be removed before compilation of the autograding
-executables.  
+executables.
+
+Submitty also supports C/C++ preprocessor `#include` directives in
+`config.json`. This can be used to split a large autograding
+configuration across multiple files and reuse common fragments across
+gradeables.
+
+If a build or validation error points to a line number that does not
+match the file you edited, compare it against the generated /
+preprocessed config used during the build. If your build log includes
+generated config sections, those files can make debugging much easier.
+
+See the
+[multi-file autograding example](https://github.com/Submitty/Submitty/tree/main/more_autograding_examples/multifile_config_python_greeting)
+for a concise example that uses `#include`.
 
 
 * **field:** ``"testcases"``  
@@ -268,4 +282,3 @@ executables.
 * **field:** ``"textboxes"``  
   **type:** _array of textbox objects_  (Described below)  
   **default value:** ``empty``  
-