Change group function EQUAL to EQUALITY (openhab#783)

Relates to eclipse-archived/smarthome#6278.

Signed-off-by: Henning Treu <[email protected]>

configuration/items.md

@@ -467,14 +467,14 @@ The general syntax for groups with a specific item type and aggregation function
 Group[:itemtype[:function]] groupname ["labeltext"] [<iconname>] [(group1, group2, ...)]
 ```
 
-- If the aggregation function is omitted, the function `EQUAL` will be used
-- If the aggregation function and `itemtype` are omitted, no group state will be aggregated from member Items
+- If the aggregation function is omitted, the function `EQUALITY` will be used.
+- If the aggregation function and `itemtype` are omitted, no group state will be aggregated from member Items.
 
 Group state aggregation functions can be any of the following:
 
 | Function               | Description |
 |------------------------|-------------|
-| `EQUAL`                | Default if no function is specified. If ALL members have state X the group state will be X, otherwise the group state will be `UNDEF`. |
+| `EQUALITY`             | Default if no function is specified. If ALL members have state X the group state will be X, otherwise the group state will be `UNDEF`. |
 | `AND(value1,value2)`  | [Boolean](https://en.wikipedia.org/wiki/Boolean_algebra) AND operation. If all item states are 'value1', 'value1' is returned, otherwise 'value2' is returned. |
 | `OR(value1,value2)`   | [Boolean](https://en.wikipedia.org/wiki/Boolean_algebra) OR operation. If at least one item state is of 'value1', 'value1' is returned, otherwise 'value2' is returned. |
 | `NAND(value1,value2)` | [Boolean](https://en.wikipedia.org/wiki/Boolean_algebra) NAND (not AND) operation. Returns the opposite of the AND operation. |