DOC-9793-Completed -- Remove hydrogen references (#652)

https://issues.couchbase.com/browse/DOC-9793

Co-authored-by: bridgei@mac.com <bridgei@mac.com>

modules/ROOT/pages/upgrading.adoc

@@ -424,8 +424,8 @@ This section describes recommended upgrade strategies for implementing Inter-Syn
 .{sc1title}
 ====
 From::
-* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
-* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
+* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
+* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
 * Replication - SG Replicate configured in continuous or one-shot mode
 * Conflict resolution -- Not implemented
 
@@ -450,8 +450,8 @@ Strategy::
 .{sc2title}
 ====
 From::
-* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
-* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
+* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
+* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
 * Replication -- SG{nbsp}Replicate configured in continuous or one-shot mode
 * Conflict resolution -- Custom conflict resolution with `allow_conflicts=true`
 
@@ -479,8 +479,8 @@ Strategy::
 .{sc3title}
 ====
 From::
-* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
-* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
+* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
+* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
 * Replication -- SG{nbsp}Replicate configured in continuous or one-shot mode
 * Conflict resolution -- Not implemented
 
@@ -494,7 +494,7 @@ Strategy::
 * Upgrade sequence
 .. Stop SG{nbsp}Replicate replications
 // .. Remove the SG{nbsp}Replicate replication configuration and replace it with inter-Sync Gateway replication equivalent.
-.. Upgrade each cluster to Hydrogen.
+.. Upgrade each cluster to 2.8.
 * Restart Outcomes
 ** When The active cluster is restarted it will automatically switch to Inter-Sync Gateway Replication
 ** Replication will continue from the last checkpoint, unless over-ridden.
@@ -513,8 +513,8 @@ Strategy::
 .{sc4-title}
 ====
 From::
-* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
-* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-Hydrogen)
+* Source Cluster -- Active peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
+* Target Cluster -- Passive peer running Sync Gateway 2.x or 1.5 (Pre-2.8)
 * Replication -- SG{nbsp}Replicate configured in continuous or one-shot mode
 * Conflict resolution -- Custom conflict resolution with `allow_conflicts=true`
 
@@ -530,7 +530,7 @@ Strategy::
 .. Stop SG{nbsp}Replicate replications
 // .. Remove the SG{nbsp}Replicate replication configuration
 .. Add the Inter-Sync Gateway replication configuration, including Javascript function as {configuration-properties-legacy--xref--db-rep-resolver}
-.. Upgrade each cluster to Hydrogen
+.. Upgrade each cluster to 2.8
 * Restart Outcomes
 ** When the active cluster is restarted it will automatically switch to Inter-Sync Gateway Replication
 ** Replication will continue from the last checkpoint, unless over-ridden.