Add information regarding version-specific differences (#33)

Author: iljarotar

README.md

@@ -24,6 +24,8 @@ DEVICE_TYPE=LeafRouter
 ASIC_TYPE=broadcom
 ```
 
+3. The `/etc/sonic/sonic_version.yml` file includes the build branch of the current SONiC version. This information is necessary for version-specific configuration.
+
 ## Configuration Parameters
 
 ### bgp_ports
@@ -208,6 +210,8 @@ Result:
 }
 ```
 
+Depending on the SONiC version, the resulting field names in may slightly differ.
+
 ### looback_address
 
 Example:
@@ -474,6 +478,8 @@ For each port that is not explicitly configured in `breakouts` and `ports` an en
 
 ### sag
 
+SAG configuration is only supported for SONiC versions from the `ec202211_ecsonic` build branch.
+
 Example:
 
 ```yaml
@@ -582,13 +588,13 @@ vlans:
       - 10.9.8.7
       - 10.9.8.6
     ip: 10.9.7.0
-    sag: true
+    sag: true # only for ec202211_ecsonic branch
     tagged_ports:
       - PortChannel01
     untagged_ports:
       - PortChannel11
     vrf: Vrf45
-    vrrp:
+    vrrp: # only for ec202111 branch
       group: 1
       priority: 66
       ip: 10.255.1.1/24
@@ -620,10 +626,10 @@ Result:
     }
   },
   "VRRP_INTERFACE": {
-      "Vrrp1-v4": {
-          "parent_interface": "Vlan4000"
-      },
-      "Vrrp1-v4|10.255.1.1/24": {}
+    "Vrrp1-v4": {
+      "parent_interface": "Vlan4000"
+    },
+    "Vrrp1-v4|10.255.1.1/24": {}
   }
 }
 ```

configdb/configdb.go

@@ -506,7 +506,7 @@ func getPortsAndBreakouts(ports values.Ports, breakouts map[string]string, platf
 
 func getSAG(sag *values.SAG, version *v.Version) (*SAG, error) {
 	if version.Branch != string(v.Branch202211) && sag != nil {
-		return nil, fmt.Errorf("sag configuration only works with sonic versions from the ec202211 branch")
+		return nil, fmt.Errorf("sag configuration only works with sonic versions from the ec202211_ecsonic branch")
 	}
 
 	if sag == nil || sag.MAC == "" {
@@ -540,7 +540,7 @@ func getVLANInterfaces(vlans []values.VLAN, version *v.Version) (map[string]VLAN
 		var vlanInterface VLANInterface
 
 		if version.Branch != string(v.Branch202211) && vlan.SAG != nil {
-			return nil, fmt.Errorf("sag only works for sonic builds from branch 202211")
+			return nil, fmt.Errorf("sag only works for sonic builds from branch ec202211_ecsonic")
 		}
 		var sag string
 		if vlan.SAG != nil {