Add docs for combining output parser

docs/docs/modules/prompts/output_parsers/index.mdx

@@ -1,5 +1,4 @@
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-hide_table_of_contents: true
 sidebar_label: Output Parsers
 sidebar_position: 2
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@@ -56,3 +55,11 @@ This output parser can be used when you want to return a list of items.
 import Comma from "@examples/prompts/comma_list_parser.ts";
 
 <CodeBlock language="typescript">{Comma}</CodeBlock>
+
+## Combinining Output Parsers
+
+Output parsers can be combined using `CombininingOutputParser`. This output parser takes in a list of output parsers, and will ask for (and parse) a combined output that contains all the fields of all the parsers.
+
+import Combining from "@examples/prompts/combining_parser.ts";
+
+<CodeBlock language="typescript">{Combining}</CodeBlock>