doc: add documentation for using CPM.

doc/building-corrade.dox

@@ -71,6 +71,7 @@ platforms.
 -   @ref building-corrade-packages-gentoo
 -   @ref building-corrade-packages-rpm
 -   @ref building-corrade-packages-brew
+-   @ref building-corrade-packages-cpm
 -   @ref building-corrade-packages-vcpkg
 -   @ref building-corrade-packages-conan
 -   @ref building-corrade-packages-hunter
@@ -235,6 +236,36 @@ If you want to pass additional flags to CMake or
 @ref building-corrade-features "enable / disable additional features", edit the
 `*.rb` file.
 
+@subsection building-corrade-packages-cpm CMake Package Manager / CPM
+
+If you're using [CPM](https://github.com/cpm-cmake/CPM.cmake), adding Corrade
+as a dependency can be done with the following. If you're fetching the `master`
+branch, it's recommended to disable `GIT_SHALLOW` to perform a full clone
+including all tags. If not, the build prints a warning about being unable to
+fetch a Git version for the `version.h` header, and will generate a fallback
+file instead.
+
+@code{.cmake}
+CPMAddPackage(
+    NAME corrade
+    GIT_REPOSITORY https://github.com/mosra/corrade.git
+    GIT_TAG master
+    GIT_SHALLOW NO)
+@endcode
+
+If you want to pass additional flags to CMake or
+@ref building-corrade-features "enable / disable additional features", pass
+then via `OPTIONS`, for example:
+
+@code{.cmake}
+CPMAddPackage(
+    NAME corrade
+    ...
+    OPTIONS
+        "CORRADE_BUILD_DEPRECATED OFF"
+        "CORRADE_WITH_INTERCONNECT OFF")
+@endcode
+
 @subsection building-corrade-packages-vcpkg Vcpkg package
 
 Corrade is available as a [Vcpkg](https://github.com/Microsoft/vcpkg) package.