Organize Iris support files

docs/EXPLORER.md

@@ -247,8 +247,9 @@ is a unit test with exactly those names in it.
 
 ### 12. Icons
 
-Added to `NerdIcons.kt` **and** `build-icon-font.sh`, then the script rerun
-and its output committed: `md-folder` U+F024B (the header button and
+Add these to `iris/core/src/icon.rs` **and**
+`iris/core/build-icon-font.sh`, then rerun the script and commit its output:
+`md-folder` U+F024B (the header button and
 directory rows), `md-plus` U+F0415, `md-pencil` U+F03EB,
 `md-content_save` U+F0193, `md-file_outline` U+F0224. The folder and the plus
 are the same codepoints dev-updater uses and must not drift from it, as the