add runtime destination for install target (#47)

CMakeLists.txt

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6096a7d..0e1ea1b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,5 +60,5 @@
             picoboot_connection_cxx
             ${LIBUSB_LIBRARIES})
     # allow `make install`
-    install(TARGETS picotool)
+    install(TARGETS picotool RUNTIME DESTINATION bin)
 endif()