build: trigger reconfigure on VERSION change; make api docs install OPTIONAL

CMakeLists.txt

@@ -1,4 +1,6 @@
 cmake_minimum_required(VERSION 3.20)
+set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS
+    "${CMAKE_CURRENT_SOURCE_DIR}/VERSION")
 file(READ "${CMAKE_CURRENT_SOURCE_DIR}/VERSION" SVAPI_VERSION)
 string(STRIP "${SVAPI_VERSION}" SVAPI_VERSION)
 project(smartbotic-vectorapi VERSION ${SVAPI_VERSION} LANGUAGES CXX)
@@ -56,4 +58,5 @@ install(FILES ${CMAKE_SOURCE_DIR}/config/config.json
     DESTINATION ${CMAKE_INSTALL_SYSCONFDIR}/smartbotic-vectorapi)
 install(FILES ${CMAKE_SOURCE_DIR}/api/openapi.json
               ${CMAKE_SOURCE_DIR}/api/llms.txt
-    DESTINATION ${CMAKE_INSTALL_DATADIR}/smartbotic-vectorapi)
+    DESTINATION ${CMAKE_INSTALL_DATADIR}/smartbotic-vectorapi
+    OPTIONAL)