docs: Update changelog and updating guide

Author: AntonioND

docs/content/docs/changelog.md

@@ -24,6 +24,8 @@ weight: 6
     because too many projects use it.
   - Add warning to material `GL_SHININESS` because it isn't used for anything.
   - Align the Huffman temporary buffer to a word just in case it's needed.
+  - Stop expecting a size field in the `GRF` chunk of GRF files.
+  - Support `PIDX` chunks in GRF files.
 
 - DSWiFi:
 
@@ -39,6 +41,9 @@ weight: 6
 
 - grit:
 
+  - Remove size field from `GRF` chunks in GRF files. This was added by BlocksDS
+    and it makes it harder to be compatible with other GRF files. Removing it
+    doesn't affect anything because the RIFF chunk already has the size.
   - When exporting tiled backgrounds grit didn't check if the size of the tile
     set was too big. There was a check but it was incorrect. Now, grit will fail
     if it's trying to export too many tiles for the specified format. For

docs/content/docs/guides/updating_guide.md

@@ -22,6 +22,13 @@ including additions and enhancements to the SDK which are not listed here.
   games, but it's important to check all images that fail to be converted
   because they weren't being converted correctly before.
 
+* The "size" field of `GRF` chunks in GRF files has been removed. This field was
+  added in one of the initial versions of BlocksDS, and it makes it harder to
+  support old and new files simultaneously. Programs using `grit`, `ptexconv`
+  and the libnds helpers to load GRF files will need to rebuild all their
+  graphics. Programs with custom parsers will need to modify their parsers to
+  remove that field.
+
 ### Upgrading to BlocksDS 1.15.2
 
 * The DSWiFi structs `Wifi_TxHeader` and `Wifi_RxHeader` are now private. They