linkbox: document lower cased extensions and name(1) renames

Linkbox converts file extensions to lower case on upload, and renames an
uploaded file to name(1) if its name is the start of the name of a file
already in the directory, e.g. "apple" next to "applebanana". Document
both and ignore the TestTransform cases which they break.

docs/content/linkbox.md

@@ -138,3 +138,12 @@ Properties:
 
 Invalid UTF-8 bytes will also be [replaced](https://rclone.org/overview/#invalid-utf8),
 as they can't be used in JSON strings.
+
+Linkbox converts file extensions to lower case on upload, so a file
+uploaded as `file.TXT` is stored as `file.txt`.
+
+Linkbox renames an uploaded file to `name(1)` if its name is the start
+of the name of a file already in the same directory, for example when
+uploading `apple` to a directory containing `applebanana`. rclone then
+can't find the file it uploaded and the upload fails with `object not
+found`.

fstest/test_all/config.yaml

@@ -598,6 +598,8 @@ backends:
      - TestFixCase
      - TestListDirSorted        # Can't upload files starting with . - FIXME fix with encoding
      - TestListDirSortedFn      # Can't upload files starting with . - FIXME fix with encoding
+     - TestTransform/suffix     # Linkbox lower cases file extensions
+     - TestTransform/truncate   # Linkbox renames a file whose name prefixes another to name(1)
      - TestSyncOverlapWithFilter # Can't upload files starting with . - FIXME fix with encoding
    ignoretests:
      - cmd/bisync