doc: fix back-references and stale claims left by the conversion

Reference sections kept pointing at the line-based format they no longer
document.  `sysv` and `task` sent the reader to Services for "<COND>",
the cgroups chapter opened by listing three legacy directives and then
explained further down that only two of them exist here, and the logging
chapter still gave "log:prio:facility.level,tag:ident" as the full
syntax.

Some claims were wrong independent of the format:

  - a sysv is a supervised daemon, grouped with service in
    SVC_TYPE_DAEMON, not a variation on task
  - restart-max has no upper bound of 255, or any other
  - the built-in rescue fallback runs in 12345789, not 12345
  - conditional loading quotes system/10-hotplug.conf, not
    system/hotplug.conf
  - the key spells conflicts, not conflict
  - the built-in getty no longer wants TERM last, it is a key

`if` takes either a service name or, in angle brackets, a condition,
decided in svc_ifthen().  Only the examples showed this, so it is now
said.

Terminology follows the split index.md already draws: a block is the new
format, a stanza the line-based one.

src/rescue.conf was still line-based, missed because it sits in src/
rather than system/ or contrib/.

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

doc/config/task-and-run.md

@@ -3,7 +3,8 @@ run (sequence)
 
 **Syntax:** `run NAME { command = "/path/to/cmd ARGS" }`
 
-> `<COND>` is described in the [Services](services.md) section.
+> Conditions, runlevels, and the other settings a `run` block takes are
+> described in [Service Options](service-opts.md).
 
 One-shot command to run in sequence when entering a runlevel, with
 optional arguments and description.  `run` commands are guaranteed to be
@@ -33,7 +34,8 @@ task (parallel)
 
 **Syntax:** `task NAME { command = "/path/to/cmd ARGS" }`
 
-> `<COND>` is described in the [Services](services.md) section.
+> A `task` block takes the same settings as `run`, see
+> [Service Options](service-opts.md).
 
 One-shot like 'run', but starts in parallel with the next command.
   
@@ -93,7 +95,7 @@ The firewall rules are created once.  The `exec-stop-post` script runs when
 entering runlevel 0 (halt) or 6 (reboot), or on explicit stop.
 
 > [!NOTE]
-> The `remain-after-exit` option is not supported for bootstrap-only
+> The `remain-after-exit` setting is not supported for bootstrap-only
 > tasks (tasks with only runlevel S).  Bootstrap tasks are deleted
 > immediately after completion, and their `exec-stop-post` scripts never
 > run.  A warning is logged if `remain-after-exit` is used on such tasks.