minor #2938 [Icons] Document icon_sets configuration (Kocal)

This PR was merged into the 2.x branch.

Discussion
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[Icons] Document `icon_sets` configuration

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Docs?         | yes <!-- required for new features -->
| Issues        | Fix #2182 <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT

Related to #2156

Commits
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4f4eb76 [Icons] Document `icon_sets` configuration

Author: Kocal

src/Icons/CHANGELOG.md

@@ -14,10 +14,11 @@ We recommend you to **lock** your icons **before** upgrading to UX Icons 2.24. W
 
 -   Add `aliases` configuration option to define icon alternative names.
 -   Add support for `int` and `float` attribute values in `<twig:ux:icon />`.
+-   Add support for Icon sets, configurable with `icon_sets` option.
 
 ## 2.19.0
 
--   Add `ignore_not_found` option to silence error during rendering if the 
+-   Add `ignore_not_found` option to silence error during rendering if the
     icon is not found.
 
 ## 2.17.0

src/Icons/doc/index.rst

@@ -628,6 +628,21 @@ Full Configuration
         # Whether to ignore errors when an icon is not found
         ignore_not_found: false
 
+        # Icon sets configuration, array of prefix => icon set configuration
+        icon_sets:
+            # Icon set for "flags", can be used like this: ux_icon('flags:fr')
+            flags:
+                It can either be mapped to a local directory...
+                path: '%kernel.project_dir%/assets/images/flags'
+                ... or to an existing icon set identifier
+                alias: 'lucide'
+
+                # Override the default attributes (default_icon_attributes) for this icon set
+                icon_attributes:
+                    class: 'flag'    # Replace the default class
+                    stroke: 'none'      # Add a new attribute
+                    fill: false         # Use "false" to remove a default attribute
+
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