Update docs

README.md

@@ -253,6 +253,30 @@ WARNING: It's important to get this right, because if the specified derivative i
 image for any reason, the ORIGINAL will be downloaded - which will lead to slow chooser response times and higher memory
 usage when generating renditions.
 
+### `BYNDER_MAX_DOCUMENT_FILE_SIZE`
+
+Example: `10485760`
+
+Default: `5242880`
+
+The maximum acceptable file size (in Bytes) when downloading a 'Document' asset from Bynder. This is safety measure to guard your Wagtail project against memory spikes when file contents is loaded into memory, and can be tweaked for individual environments to reflect:
+- How much RAM is available in the host infrastructure
+- How large the documents are that editors want to feature in content
+- Whether you are doing anything particularly memory intensive with document files (e.g. text/content analysis)
+
+
+### `BYNDER_MAX_IMAGE_FILE_SIZE`
+
+Example: `10485760`
+
+Default: `5242880`
+
+The maximum acceptable file size (in Bytes) when downloading an 'Image' asset from Bynder. This is safety measure to guard your Wagtail project against memory spikes when file contents is loaded into memory.
+
+This setting is provided separately to `BYNDER_MAX_DOCUMENT_FILE_SIZE`, because it often needs to be set to a lower value, even if enough RAM is available to hold the orignal file in memory. This is because server-size image libraries have to understand the individual pixel values of the image, which often requires much more memory than that of the original contents.
+
+As with `BYNDER_MAX_DOCUMENT_FILE_SIZE`, this can be tweaked for individual environments to reflect how much RAM is available in the host infrastructure.
+
 ### `BYNDER_VIDEO_MODEL`
 
 Example: `"video.Video"`