Update submission/preparation-guide.qmd

Co-authored-by: Malin Klang <[email protected]>

submission/preparation-guide.qmd

@@ -27,7 +27,7 @@ Before you submit your data, please make sure
 2. All the files should be encrypted with crypt4gh and the extensions must be `c4gh`, e.g:
 `images.xml.c4gh`, `image1.dcm.c4gh` etc
 3. The metadata is stored in a folder called `metadata` under the root of the submission folder.
-4. The only files that should exist in the `metadata` folder are the following: `dac.xml`, `dataset.xml`, `images.xml`, `observations.xml`, `observers.xml`, `policy.xml`, `samples.xml` and `study.xml`.
+4. The only files that may exist in the `metadata` folder are the following: `dac.xml`, `dataset.xml`, `images.xml`, `observations.xml`, `observers.xml`, `policy.xml`, `samples.xml` and `study.xml`.
 5. The file `images.xml.c4gh` should include the full path of each dicom image and includes also the checksums of both encrypted and unencrypted files, e.g:
 ```
     <FILES>