Keep "hosts Chatbot" in IceGrid Greeter diagrams

Per review feedback: Chatbot is the Greeter implementation the server
hosts, so "hosts Chatbot" is correct. Reverts that diagram-label change
across the C#, Java, MATLAB, PHP, Ruby, and Swift IceGrid Greeter READMEs
(the Swift Mermaid dotted-arrow fix is kept).

Author: pepone

csharp/IceGrid/Greeter/README.md

@@ -10,7 +10,7 @@ flowchart LR
         Locator[locator:4061]
     end
     Node[IceGrid Node]
-    Server(Server<br/>hosts Greeter)
+    Server(Server<br/>hosts Chatbot)
     Registry <--> Node --> | activate | Server
     Locator -.-> |return greeter endpoints | Client
     Client ==> |greet request| Server

java/IceGrid/greeter/README.md

@@ -10,7 +10,7 @@ flowchart LR
         Locator[locator:4061]
     end
     Node[IceGrid Node]
-    Server(Server<br/>hosts Greeter)
+    Server(Server<br/>hosts Chatbot)
     Registry <--> Node --> | activate | Server
     Locator -.-> |return greeter endpoints | Client
     Client ==> |greet request| Server

matlab/IceGrid/greeter/README.md

@@ -10,7 +10,7 @@ flowchart LR
         Locator[locator:4061]
     end
     Node[IceGrid Node]
-    Server(Server<br/>hosts Greeter)
+    Server(Server<br/>hosts Chatbot)
     Registry <--> Node --> | activate | Server
     Locator -.-> |return greeter endpoints | Client
     Client ==> |greet request| Server

php/IceGrid/greeter/README.md

@@ -10,7 +10,7 @@ flowchart LR
         Locator[locator:4061]
     end
     Node[IceGrid Node]
-    Server(Server<br/>hosts Greeter)
+    Server(Server<br/>hosts Chatbot)
     Registry <--> Node --> | activate | Server
     Locator -.-> |return greeter endpoints | Client
     Client ==> |greet request| Server

ruby/IceGrid/greeter/README.md

@@ -10,7 +10,7 @@ flowchart LR
         Locator[locator:4061]
     end
     Node[IceGrid Node]
-    Server(Server<br/>hosts Greeter)
+    Server(Server<br/>hosts Chatbot)
     Registry <--> Node --> | activate | Server
     Locator -.-> |return greeter endpoints | Client
     Client ==> |greet request| Server

swift/IceGrid/Greeter/README.md

@@ -10,7 +10,7 @@ flowchart LR
         Locator[locator:4061]
     end
     Node[IceGrid Node]
-    Server(Server<br/>hosts Greeter)
+    Server(Server<br/>hosts Chatbot)
     Registry <--> Node --> | activate | Server
     Locator -.-> |return greeter endpoints | Client
     Client ==> |greet request| Server