At runtime, Vim checks if the command table needs to be updated in the function find_command() (src/ex_docmd.c).
The Makefile contains the target cmdidxs which creates the the ex_cmdidxs.h file:
$ make cmdidxs
Unfortunately, I was unable to execute this make command on Wndows. Because the Makefile just executes the following line, it can also be copied and pasted: