Improve docs about running test/info executables on embedded platforms.

src/Magnum/Audio/al-info.cpp

@@ -50,6 +50,15 @@ Arguments:
 -   `--extension-strings` --- list all extension strings provided by the driver
     (implies `--short`)
 
+@subsection magnum-al-info-usage-emscripten Usage on Emscripten
+
+When installing Magnum, point the `MAGNUM_DEPLOY_PREFIX` CMake variable to your
+webserver location. The Magnum Info utility is then available in a `magnum-al-info/`
+subdirectory of given location. You can pass all command-line arguments from
+above to it via GET parameters. See the relevant section of
+@ref Platform-WindowlessEglApplication-usage-emscripten "WindowlessEglApplication documentation"
+for more information.
+
 @section magnum-al-info-example Example output
 
 @code{.shell-session}

src/Magnum/OpenGLTester.h

@@ -84,6 +84,24 @@ corrade_add_test(YourTest YourTest.cpp LIBRARIES Magnum::OpenGLTester)
 
 See @ref building, @ref cmake and @ref testsuite for more information.
 
+@section OpenGLTester-running Running the test executables
+
+Implicitly, running the test executables requires presence of a GPU with OpenGL
+drivers. In addition, on desktop, unless Magnum is built with
+`MAGNUM_TARGET_HEADLESS`, OpenGL context creation requires a graphical desktop
+to be running. On embedded systems (and @ref CORRADE_TARGET_IOS "iOS",
+@ref CORRADE_TARGET_ANDROID "Android" in particular) running the tests has no
+special requirements.
+
+On virtualized systems and systems without a GPU (e.g. CI servers) it's
+possible to link against e.g. Mesa softpipe or
+[SwiftShader](https://github.com/google/swiftshader), but be prepared to expect
+reduced performance, reduced feature set and possible non-comformant behavior
+on such drivers.
+
+See @ref TestSuite-Tester-running for more information about running the tests
+on particular platforms.
+
 @section OpenGLTester-context OpenGL context creation
 
 Upon construction the class creates an OpenGL context, meaning you don't have

src/Magnum/Platform/info.cpp

@@ -102,6 +102,30 @@ Arguments:
 -   `--limits` --- display also limits and implementation-defined values
 -   `--magnum-...` --- engine-specific options (see @ref Context for details)
 
+@subsection magnum-info-usage-emscripten Usage on Emscripten
+
+When installing Magnum, point the `MAGNUM_DEPLOY_PREFIX` CMake variable to your
+webserver location. The Magnum Info utility is then available in a `magnum-info/`
+subdirectory of given location. You can pass all command-line arguments from
+above to it via GET parameters. See the relevant section of
+@ref Platform-WindowlessEglApplication-usage-emscripten "WindowlessEglApplication documentation"
+for more information.
+
+@subsection magnum-info-usage-android Usage on Android
+
+When you have developer-enabled Android device connected or Android emulator
+running, you can use ADB to upload the built executable to device temp
+directory and run it on the device:
+
+@code{.sh}
+adb push build-android-arm64/src/Magnum/Platform/magnum-info /data/local/tmp
+adb shell /data/local/tmp/magnum-info
+@endcode
+
+You can also use @cb{.sh} adb shell @ce to log directly into the device shell
+and continue from there. All @ref magnum-info-usage "command-line" arguments
+are supported.
+
 @section magnum-info-example Example output
 
 @code{.shell-session}