docs: update docs on label-sources option

Update documentation on core.labelSources/core.sources config file
options and -label-sources/-sources command line flags.

docs/advanced/worker-commandline-reference.md

@@ -136,12 +136,14 @@ Example:
 nfd-worker -server-name-override=localhost
 ```
 
-### -sources
+### -label-sources
 
-The `-sources` flag specifies a comma-separated list of enabled feature
-sources. A special value `all` enables all feature sources.
+The `-label-sources` flag specifies a comma-separated list of enabled label
+sources. A special value `all` enables all sources. Consider using the
+`core.labelSources` config file option, instead, allowing dynamic
+configurability.
 
-Note: This flag takes precedence over the `core.sources` configuration
+Note: This flag takes precedence over the `core.labelSources` configuration
 file option.
 
 Default: all
@@ -149,11 +151,12 @@ Default: all
 Example:
 
 ```bash
-nfd-worker -sources=kernel,system,local
+nfd-worker -label-sources=kernel,system,local
 ```
 
-**DEPRECATED**: you should use the `core.sources` option in the
-configuration file, instead.
+### -sources
+
+**DEPRECATED**: use [`-label-sources`](#-label-sources) instead.
 
 ### -no-publish
 

docs/advanced/worker-configuration-reference.md

@@ -43,13 +43,12 @@ core:
   sleepInterval: 60s
 ```
 
-### core.sources
+### core.labelSources
 
-`core.sources` specifies the list of enabled feature sources. A special value
-`all` enables all feature sources.
+`core.labelSources` specifies the list of enabled label sources. A special
+value `all` enables all sources.
 
-Note: Overridden by the deprecated `-sources` command line flag (if
-specified).
+Note: Overridden by the `-label-sources` command line flag (if specified).
 
 Default: `[all]`
 
@@ -62,6 +61,13 @@ core:
     - custom
 ```
 
+### core.sources
+
+**DEPRECATED**: use [`core.labelSources`](#core.labelSources) instead.
+
+Note: `core.sources` takes precedence over the `core.labelSources`
+configuration file option.
+
 ### core.labelWhiteList
 
 `core.labelWhiteList` specifies a regular expression for filtering feature

docs/get-started/features.md

@@ -50,7 +50,8 @@ The last component (i.e. `attribute-name`) is optional, and only used if a
 feature logically has sub-hierarchy, e.g. `sriov.capable` and
 `sriov.configure` from the `network` source.
 
-The `-sources` flag controls which sources to use for discovery.
+The `-label-sources` flag controls which sources to enable for label
+generation.
 
 *Note: Consecutive runs of nfd-worker will update the labels on a
 given node. If features are not discovered on a consecutive run, the corresponding