Platform: CMAKE_TOOLCHAIN_FILE should be always absolute.

src/Magnum/Platform/EmscriptenApplication.h

@@ -93,7 +93,7 @@ webserver, e.g.  `/srv/http/emscripten`).
 @code{.sh}
 mkdir build-emscripten && cd build-emscripten
 cmake .. \
-    -DCMAKE_TOOLCHAIN_FILE="../toolchains/generic/Emscripten.cmake" \
+    -DCMAKE_TOOLCHAIN_FILE=path/to/toolchains/generic/Emscripten-wasm.cmake \
     -DCMAKE_PREFIX_PATH=/usr/lib/emscripten/system \
     -DCMAKE_INSTALL_PREFIX=/srv/http/emscripten
 cmake --build .

src/Magnum/Platform/Sdl2Application.h

@@ -160,7 +160,7 @@ you have all the dependencies.
 @code{.sh}
 mkdir build-ios && cd build-ios
 cmake .. \
-    -DCMAKE_TOOLCHAIN_FILE=../toolchains/generic/iOS.cmake \
+    -DCMAKE_TOOLCHAIN_FILE=path/to/toolchains/generic/iOS.cmake \
     -DCMAKE_OSX_SYSROOT=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk \
     -DCMAKE_OSX_ARCHITECTURES="arm64;armv7;armv7s" \
     -DCMAKE_PREFIX_PATH=~/ios-libs \