add documentation for desired_state filter

Signed-off-by: Harald Albers <github@albersweb.de>

docs/reference/commandline/node_ls.md

@@ -44,7 +44,6 @@ The currently supported filters are:
 * name
 * id
 * label
-* desired_state
 
 ### name
 

docs/reference/commandline/node_tasks.md

@@ -41,12 +41,12 @@ than one filter, then pass multiple flags (e.g., `--filter "foo=bar" --filter "b
 
 The currently supported filters are:
 
-* name
-* id
-* label
-* desired_state
+* [name](#name)
+* [id](#id)
+* [label](#label)
+* [desired_state](#desired_state)
 
-### name
+#### name
 
 The `name` filter matches on all or part of a task's name.
 
@@ -61,7 +61,7 @@ The following filter matches all tasks with a name containing the `redis` string
     0tgctg8h8cech4w0k0gwrmr23  redis.10  redis    redis:3.0.6  Running 5 seconds   Running        swarm-manager1
 
 
-### id
+#### id
 
 The `id` filter matches a task's id.
 
@@ -85,6 +85,11 @@ bg8c07zzg87di2mufeq51a2qp  redis.7  redis    redis:3.0.6  Running 9 minutes   Ru
 ```
 
 
+#### desired_state
+
+The `desired_state` filter can take the values `running` and `accepted`.
+
+
 ## Related information
 
 * [node inspect](node_inspect.md)

docs/reference/commandline/service_tasks.md

@@ -60,6 +60,7 @@ The currently supported filters are:
 
 * [id](#id)
 * [name](#name)
+* [desired_state](#desired_state)
 
 
 #### ID
@@ -84,6 +85,11 @@ ID                         NAME      SERVICE  IMAGE        DESIRED STATE  LAST S
 ```
 
 
+#### desired_state
+
+The `desired_state` filter can take the values `running` and `accepted`.
+
+
 ## Related information
 
 * [service create](service_create.md)