[ENH] Add human statement to emphasize that _desc is the last entity

src/derivatives/common-data-types.md

@@ -25,7 +25,7 @@ A guide for using macros can be found at
 Preprocessed `bold` NIfTI file in the original coordinate space of the original run.
 The location of the file in the original datasets is encoded in the `Sources` metadata,
 and [`_desc-<label>`](../appendices/entities.md#desc)
-is used to prevent clashing with the original filename.
+is used (the last entity before the suffix) to prevent clashing with the original filename.
 
 <!-- This block generates a file tree.
 A guide for using macros can be found at

src/schema/rules/entities.yaml

@@ -31,4 +31,7 @@
 - resolution
 - density
 - label
+# NOTE: there is a current convention to keep description to be the last entity.
+# If to be changed - potentially might need to adjust text, e.g. now in
+# src/derivatives/common-data-types.md
 - description