docs: Update manual with 1.12 changelog

docs/manual.adoc

@@ -2138,6 +2138,27 @@ Because of the differences in document object models, performance considerations
 
 :!numbered:
 
+[[v1.12]]
+=== v1.12 ^2022-02-09^
+
+Maintenance release. Changes:
+
+* Bug fixes:
+    . Fix a bug in xml_document move construction when the source of the move is empty
+    . Fix const-correctness issues with iterator objects to support C++20 ranges
+
+* XPath improvements:
+    . Improved detection of overly complex queries that may result in stack overflow during parsing
+
+* Compatibility improvements:
+    . Fix Cygwin support for DLL builds
+    . Fix Windows CE support
+    . Add NuGet builds and project files for VS2022
+
+* Build system changes
+    . All CMake options now have the prefix `PUGIXML_`. This may require changing dependent build configurations.
+    . Many build settings are now exposed via CMake settings, most notably `PUGIXML_COMPACT` and `PUGIXML_WCHAR_MODE` can be set without changing `pugiconfig.hpp`
+
 [[v1.11]]
 === v1.11 ^2020-11-26^