readme: build: update to reflect recent 'make' PREFIX and install changes

README.md

@@ -7,17 +7,11 @@ time in userspace is kept in present time.
 
 ## Build
 The repository contains a simple Makefile. By `make install` the two
-shell scripts get installed to `/sbin`. Adding `PREFIX=/usr` places them
-to `/usr/sbin`. Variable `DESTDIR` allows to change the install path to
-something like `DESTDIR=$pkgdir`.
+shell scripts get installed to `/usr/bin`. Variable `DESTDIR` allows to change
+the install path to something like `DESTDIR=$pkgdir`.
 
-To install the two OpenRC service files, perform `make install_openrc`.
-They get installed to `/etc/init.d`. Variable `DESTDIR` applies here as
-well, `PREFIX` does not.
-
-To install the systemd service files, perform `make install_systemd`.
-They get installed to `/lib/systemd/system`. Variable `DESTDIR` applies here as
-well, `PREFIX` does not.
+Both the OpenRC and systemd service files are installed by `make install`.
+Downstream packaging can choose to distribute one set, both, or none.
 
 ## Managing OpenRC services
 After installing the files, OpenRC services need to be set accordingly.