[PATCH docs 1/2] ha-manager: reword ha resources section

[Daniel Kral <d.kral@proxmox.com>]

Focus on the introduction of the HA resource concept first and what an
HA resource represents in the broader Proxmox VE context, while
introducing the service ID only in a later chapter.

Remove the comparison with `rgmanager` as it's quite dated already and
seemingly unused as it seems to be replaced by pacemaker in newer
versions of RHEL.

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
---
 ha-manager.adoc | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/ha-manager.adoc b/ha-manager.adoc
index a1b2210..6bf4e69 100644
--- a/ha-manager.adoc
+++ b/ha-manager.adoc
@@ -126,18 +126,14 @@ the linux kernel software watchdog (`softdog`).
 Resources
 ---------
 
-We call the primary management unit handled by `ha-manager` a
-resource. A resource (also called ``service'') is uniquely
-identified by a service ID (SID), which consists of the resource type
-and a type specific ID, for example `vm:100`. That example would be a
-resource of type `vm` (virtual machine) with the ID 100.
-
-For now we have two important resources types - virtual machines and
-containers. One basic idea here is that we can bundle related software
-into such a VM or container, so there is no need to compose one big
-service from other services, as was done with `rgmanager`. In
-general, a HA managed resource should not depend on other resources.
+The HA Manager's primary management unit is called an HA resource (or
+``HA service''). Currently, an HA resource can be either a Virtual
+Machine (VM) or Linux Containers (CT).
 
+Each HA resource is uniquely identified by a service ID (`sid`), which
+consists of the resource type and a type-specific ID, which is the VMID
+for VMs and containers. For example, for the VM with VMID `100`, the
+service ID is `vm:100`.
 
 Management Tasks
 ----------------
-- 
2.47.3