new docs

Author: ldennis

docs/images/constraint-section.gif

@@ -176,7 +176,7 @@ create table t1 {
 		BUSINESS(bus_start, bus_end)
 	}
 	constraints {
-		"PK" -> no_overlap<bus_start:bus_end>
+		no_overlap "PK" -> bus_start : bus_end
 	}
 }
 ```
@@ -337,7 +337,7 @@ create table t1 {
         SYSTEM(sys_start, sys_end)
     }
     constraints {
-        "PK" -> no_overlap<bus_start:bus_end>
+        no_overlap "PK" -> bus_start : bus_end
     }
 }
 ```

docs/pages/programming/bitemporal.md

@@ -333,6 +333,13 @@ inclusive-exclusive (close-open) approach for the range. The `start` and `end` c
 "greater than all". Comdb2 also generates implicit constraint to enforce that `start` is strictly less than `end`
 for every row in the table.
 
+`no_overlap` constraints can also be used together with indexes on expressions. Simply set `start` and `end` to be
+the one of the key fields defined in the key section of the schema.
+
+Here is an example:
+
+
+
 Once a `no_overlap` constraint is defined on a key, Comdb2 enforces that there cannot be more than one rows
 with identical values in all key fields (other than `start` and `end`) in any interval range `[start, end)`.
 

docs/pages/programming/table_schema.md

@@ -503,9 +503,10 @@ set all_graphs {
   }
 
   constraint-section {
-      loop {line /keyname ->
+      loop {line {opt {line /no_overlap}}
+                 /keyname ->
                  {or {line /table-name : /keyname}
-                     {line /no_overlap /start : /end}
+                     {line /start : /end}
                  }
            }
   }