docs: Update documentation on svc conditions

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

docs/conditions.md

@@ -92,6 +92,25 @@ Built-in conditions:
   difference is that `running` tells if the NIC has link.
 
 
+Composition
+-----------
+
+The `svc/` conditions can be quite tricky to understand.  They are
+generated by the Finit `pidfile.so` plugin and are composed from the
+daemon's path and the pidfile name (and path).
+
+| **service**                          | **pid:**        | **pidfile path** | **svc condition** |
+|--------------------------------------|-----------------|------------------|-------------------|
+| /sbin/foo                            |                 | /run/foo.pid     | svc/sbin/foo      |
+| /sbin/bar -p /run/baz.pid            | pid:baz         | /run/bas.pid     | svc/sbin/baz      |
+| lxc-start -n foo -p /run/lxc/foo.pid | pid:lxc/foo.pid | /run/lxc/foo.pid | svc/lxc/foo       |
+| /usr/bin/dbus-daemon                 | pid:dbus/pid    | /run/dbus/pid    | svc/usr/bin/dbus  |
+
+Omitting the `pid:` to run/task/service/sysv stanza means Finit will
+guess the pidfile path based on `/run/` and the basename(1) of the
+program.
+
+
 Debugging
 ---------
 

docs/config.md

@@ -203,21 +203,21 @@ Syntax
 
         pid[:[/path/to/]filename[.pid]]
 
-  For example, by adding `pid:/run/foo.pid` to the service `bar` that
-  PID file will, not only be created and removed automatically, but also
-  be used by the Finit condition subsystem.  So another service/run/task
-  can depend on `<svc/foo>`.
+  For example, by adding `pid:/run/foo.pid` to the service `/sbin/bar`
+  that PID file will, not only be created and removed automatically, but
+  also be used by the Finit condition subsystem.  So a service/run/task
+  can depend on `<svc/sbin/foo>`, notice the composition of conditions.
 
-  If a service `bar` *does* maintain a PID file, but using `foo.pid`, we
-  can inform Finit of this by prepending an `!` to the argument.
+  However, if a service `bar` *does* create a PID file, using `foo.pid`,
+  we can inform Finit of this by prepending an `!`:
 
         pid:!/run/foo.pid
 
   Here Finit will *not* create/remove/touch the PID file, only use it
   for the condition handling instead of the default PID file name.
 
-  For a detailed description of conditions, and how to debug them, see
-  the [Finit Conditions](conditions.md) document.
+>  For a detailed description of conditions, and how to debug them, see
+>  the [Finit Conditions](conditions.md) document.
 
   If a service should not be automatically started, it can be configured
   as manual with the optional `manual` argument. The service can then be