[yang_models]: Updated extensions and types yang models as per review comments.

Author: maheshwari-mayank

src/sonic-yang-models/yang-models/sonic-extension.yang

@@ -15,9 +15,9 @@ module sonic-extension {
         description "First Revision";
     }
 
-	/* For complete guide of using these extensions in SONiC yangs, refer
-	SONiC yang guidelines at
-	https://github.com/Azure/SONiC/blob/master/doc/mgmt/SONiC_YANG_Model_Guidelines.md */
+    /* For complete guide of using these extensions in SONiC yangs, refer
+    SONiC yang guidelines at
+    https://github.com/Azure/SONiC/blob/master/doc/mgmt/SONiC_YANG_Model_Guidelines.md */
 
     extension key-regex-configdb-to-yang {
         description "Key regex used to convert config DB keys to YANG Config";
@@ -52,17 +52,18 @@ module sonic-extension {
     }
 
     extension custom-validation {
-        description "Extension for registering custom validation handler."; 
-        argument "handler"; 
+        description "Extension for registering custom validation handler.";
+        argument "handler";
     }
 
     extension dependent-on {
         description
-            "Extension to define dependency on other table. During create/update,
-            operation will be performed first on parent table and then on this table.
-            In delete operation, this table will be deleted first and then parent table.
-            This extension can be defined only under list. Table name should always
-            suffixed with '_LIST' as modeled in yang.
+            "Extension to define dependency on other table. During CREATE/UPDATE,
+            the action will be performed first on the Parent table and then on the
+            Dependent table. In DELETE operation, the Dependent table will be
+            deleted first and then the Parent table. This extension can be defined
+            only under List nodes. Table name should always be suffixed with '_LIST'
+            as modeled in yang.
             e.g. - dependent-on STP_LIST";
         argument "value";
     }

src/sonic-yang-models/yang-models/sonic-types.yang

@@ -118,10 +118,10 @@ module sonic-types {
             enum up;
             enum down;
         }
-		description "Operational status of an entity such as Port, MCLAG etc";
+        description "Operational status of an entity such as Port, MCLAG etc";
     }
 
-    typedef mode-enable {
+    typedef mode-status {
         type enumeration {
             enum enable;
             enum disable;
@@ -131,7 +131,7 @@ module sonic-types {
             For ex. IPv6-link-local-only, Dhcp-replay-link-select, SNMP traps etc";
     }
 
-    typedef relay-policy-action {
+    typedef dhcp-relay-policy-action {
         type enumeration {
             enum discard;
             enum append;