message: Adding info about KEM and DEM being concatenated.
diff: @@ -144,6 +144,15 @@ Tink follows the corresponding RFCs.
  ### Hybrid Encryption
  +Hybrid Encryption uses a Key Encryption Message (KEM) and a Data Encryption
  +Message (DEM). The general format is
  +
  +```
  +KEM || DEM,
  +```
  +
  +with the key type knowing how many bytes to parse for the KEM.
  +
  #### KEM
  Depending on the key type, Tink uses compressed and uncompressed elliptic curve
  