CLD: add Readme for different versions

FCCee/CLD/compact/README.md

@@ -1,4 +1,33 @@
 CLD
 ====
 
-CLD_o3_v01 : CLD option 3 includes ARC detector for PID 
+FCCee_o2_v01
+------------
+
+This option was used for flavourtagging studies with the smaller radius beampipe and vertex detector, presented in the
+(CLD Note)[https://arxiv.org/abs/1911.12230]. It reduces the radius and width of the two inner most barrel layers, and
+preserves the length of the staves.
+
+FCCee_o2_v02
+------------
+
+This model is an update of v01 with a fixed TrackerEndcapSupport
+
+FCCee_o2_v03
+------------
+
+This model was taken from FCCDetectors `FCCee_o2_v02`. It doesn't fit in the option 2 category based on its too large
+vertex detector radius. This model is _obsolete_.
+
+FCCee_o2_v04
+------------
+
+This model was taken from FCCDetectors `FCCee_o2_v03`. It presents an alternate implementation of the vertex detector
+with a smaller radius, which preserves angular coverage of the vertex barrel. Various issues of the Tracker structure
+where inherited from the FCCDetectors `FCCee_o2_v02` model.
+
+
+CLD_o3_v01
+----------
+
+CLD option 3 includes ARC detector for PID