[docs] Update
diff --git a/docs/harfbuzz-docs.xml b/docs/harfbuzz-docs.xml
index 2735338..0c462f3 100644
--- a/docs/harfbuzz-docs.xml
+++ b/docs/harfbuzz-docs.xml
@@ -136,6 +136,7 @@
       <index id="api-index-full"><title>API Index</title><xi:include href="xml/api-index-full.xml"><xi:fallback /></xi:include></index>
       <index id="deprecated-api-index" role="deprecated"><title>Index of deprecated API</title><xi:include href="xml/api-index-deprecated.xml"><xi:fallback /></xi:include></index>
 
+      <index id="api-index-2-2-0" role="2.2.0"><title>Index of new symbols in 2.2.0</title><xi:include href="xml/api-index-2.2.0.xml"><xi:fallback /></xi:include></index>
       <index id="api-index-2-1-0" role="2.1.0"><title>Index of new symbols in 2.1.0</title><xi:include href="xml/api-index-2.1.0.xml"><xi:fallback /></xi:include></index>
       <index id="api-index-2-0-0" role="2.0.0"><title>Index of new symbols in 2.0.0</title><xi:include href="xml/api-index-2.0.0.xml"><xi:fallback /></xi:include></index>
       <index id="api-index-1-9-0" role="1.9.0"><title>Index of new symbols in 1.9.0</title><xi:include href="xml/api-index-1.9.0.xml"><xi:fallback /></xi:include></index>