docs: generate docs

README.md

@@ -16,6 +16,7 @@ Utilities for manipulating data in PostgreSQL database using [Slonik](https://gi
     * [Contents](#slonik-utilities-contents)
     * [Usage](#slonik-utilities-usage)
         * [`update`](#slonik-utilities-usage-update)
+        * [`updateDistinct`](#slonik-utilities-usage-updatedistinct)
         * [`upsert`](#slonik-utilities-usage-upsert)
 
 
@@ -33,7 +34,7 @@ import {
 /**
  * @param connection Instance of Slonik connection.
  * @param {string} tableName Target table name.
- * @param {Object.<string, ValueExpression>} Object describing the desired column values.
+ * @param {Object.<string, ValueExpression>} namedValueBindings Object describing the desired column values.
  * @param {Object.<string, EqualPredicate>} [booleanExpressionValues] Object describing the boolean expression used to construct WHERE condition.
  */
 update;
@@ -97,6 +98,86 @@ WHERE
 
 ```
 
+
+<a name="slonik-utilities-usage-updatedistinct"></a>
+### <code>updateDistinct</code>
+
+```js
+import {
+  updateDistinct
+} from 'slonik-utilities';
+
+/**
+ * @param connection Instance of Slonik connection.
+ * @param {string} tableName Target table name.
+ * @param {Object.<string, ValueExpression>} namedValueBindings Object describing the desired column values.
+ * @param {Object.<string, EqualPredicate>} [booleanExpressionValues] Object describing the boolean expression used to construct WHERE condition.
+ */
+updateDistinct;
+
+```
+
+Constructs and executes `UPDATE` query matching only rows with distinct values.
+
+<a name="slonik-utilities-usage-updatedistinct-example-update-all-rows-1"></a>
+#### Example: Update all rows
+
+Operation:
+
+```js
+update(
+  connection,
+  'user',
+  {
+    givenName: 'foo'
+  }
+);
+
+```
+
+Is equivalent to:
+
+```sql
+UPDATE "user"
+SET
+  "given_name" = $1
+WHERE
+  "given_name" IS DISTINCT FROM $1;
+
+```
+
+<a name="slonik-utilities-usage-updatedistinct-example-update-rows-matching-a-boolean-where-condition-1"></a>
+#### Example: Update rows matching a boolean WHERE condition
+
+Operation:
+
+```js
+update(
+  connection,
+  'user',
+  {
+    givenName: 'foo'
+  },
+  {
+    lastName: 'bar'
+  }
+);
+
+```
+
+Is equivalent to:
+
+```sql
+UPDATE "user"
+SET
+  "given_name" = $1
+WHERE
+  "last_name" = $2 AND
+  "given_name" IS DISTINCT FROM $1;
+
+```
+
+
 <a name="slonik-utilities-usage-upsert"></a>
 ### <code>upsert</code>