Merge pull request ninja-build#1100 from nico/doc

Minor updates to the manual.

doc/manual.asciidoc

@@ -158,17 +158,13 @@ http://code.google.com/p/gyp/[gyp]:: The meta-build system used to
 generate build files for Google Chrome and related projects (v8,
 node.js).  gyp can generate Ninja files for all platforms supported by
 Chrome. See the
-http://code.google.com/p/chromium/wiki/NinjaBuild[Chromium Ninja
-documentation for more details].
+https://chromium.googlesource.com/chromium/src/+/master/docs/ninja_build.md[Chromium Ninja documentation for more details].
 
-http://www.cmake.org/[CMake]:: A widely used meta-build system that
-can generate Ninja files on Linux as of CMake version 2.8.8.  (There
-is some Mac and Windows support -- http://www.reactos.org[ReactOS]
-uses Ninja on Windows for their buildbots, but those platforms are not
-yet officially supported by CMake as the full test suite doesn't
-pass.)
+https://cmake.org/[CMake]:: A widely used meta-build system that
+can generate Ninja files on Linux as of CMake version 2.8.8.  Newer versions
+of CMake support generating Ninja files on Windows and Mac OS X too.
 
-others:: Ninja ought to fit perfectly into other meta-build software
+https://github.com/ninja-build/ninja/wiki/List-of-generators-producing-ninja-build-files[others]:: Ninja ought to fit perfectly into other meta-build software
 like http://industriousone.com/premake[premake].  If you do this work,
 please let us know!