Reloading query modules docs (#916)

* QM improvements docs

* Expand on reloading query modules docs

pages/custom-query-modules/manage-query-modules.mdx

@@ -111,7 +111,7 @@ Example of a result:
 
 ### `mg.load_all`
 
-Loads or reloads all modules.
+Loads or reloads all modules. Modules can only be reloaded when they are not in use. If any of the modules that would be reloaded are being used by another thread while this is run then this will fail with the error: `Unable to unload modules, they are currently being used`. To resolve this either rerun the procedure when the modules aren't in use or use `mg.load` to load/reload the currently unused modules.
 
 Example of a Cypher query:
 
@@ -124,7 +124,7 @@ update was successful.
 
 ### `mg.load`
 
-Loads or reloads the given module.
+Loads or reloads the given module. A module can only be reloaded if it is not in use. If the module that would be reloaded is being used by another thread while this is run then this will fail the error: `Unable to unload module 'module_name', it is currently being used`. To resolve this rerun the procedure when the module isn't in use.
 
 Example of a Cypher query: