Document client.escapeIdentifier and client.escapeLiteral

Per brianc#1978 it seems that these client APIs are undocumented. Added documentation for these functions along with some examples and relevant links.

docs/pages/apis/client.mdx

@@ -1,6 +1,7 @@
 ---
 title: pg.Client
 ---
+import { Alert } from '/components/alert.tsx'
 
 ## new Client
 
@@ -256,6 +257,28 @@ client
 
 _note: end returning a promise is only available in pg7.0 and above_
 
+## client.escapeIdentifier
+
+Escapes a string as a [SQL identifier](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS).
+
+```js
+const escpaedIdentifier = client.escapeIdentifier('FooIdentifier');
+console.log(escpaedIdentifier); // '"FooIdentifier"'
+```
+
+## client.escapeLiteral
+
+Escapes a string as a [SQL literal](https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-CONSTANTS).
+
+<Alert>
+  **Note**: Instead of manually escaping SQL literals, it is recommended to use parameterized queries. Refer to [parameterized queries](/features/queries#parameterized-query) and the [client.query](#clientquery) API for more information.
+</Alert>
+
+```js
+const escapedLiteral = client.escapeLiteral("hello \\ ' world");
+console.log(escapedLiteral); // " E'hello \\\\ '' world'"
+```
+
 ## events
 
 ### error