Update diagram syntax in how_it_works.md (#476)

Author: kjy5

docs/home/how_it_works.md

@@ -21,14 +21,12 @@ flowchart LR
         n6["Rectangle"]
         n2["Server"]
     end
-    n6["Bindings"] ---|" Manipulator 1 API "| n3
-    n1 ---|" Send Request "| n2
-    n2 ---|" Callback Response "| n1
-    n6 ---|" Manipulator 2 API "| n4
-    n3 --- n6
-    n4 --- n6
-    n2 ---|" Parse Request "| n6
-    n6 ---|" Send Response "| n2
+    n6["Bindings"] <-->|" Manipulator 1 API "| n3
+    n1 -->|" Send Request "| n2
+    n2 -->|" Callback Response "| n1
+    n6 <-->|" Manipulator 2 API "| n4
+    n2 -->|" Parse Request "| n6
+    n6 -->|" Send Response "| n2
 ```
 
 This diagram shows the high-level architecture of Ephys Link. Ephys Link acts as an intermediary between a client
@@ -73,4 +71,4 @@ Some things to notice:
 - While one command is being fulfilled, the client application can still query the manipulator's current position.
   Later, the manipulator can report when it is done and complete the movement request.
 - The manipulator often has a different API than Ephys Link (`move` vs `set_position`), but the binding handles the
-  translation.
+  translation.