DOC: adding heading level to main page

Author: bsipocz

index.md

@@ -43,6 +43,8 @@ tutorials/cloud_access/euclid-cloud-access
 
 ## Accessing Euclid data
 
+### Euclid Early Release Observation
+
 ```{toctree}
 ---
 maxdepth: 1
@@ -53,6 +55,8 @@ tutorials/euclid_access/Euclid_ERO
 
 ```
 
+### Euclid Quick Release 1
+
 ```{toctree}
 ---
 maxdepth: 1