Update bg deprecations (#1661)

* Update bg deprecations

* Update v18-migration.mdx

* Create smooth-deers-accept.md

Author: simurai

.changeset/smooth-deers-accept.md

@@ -0,0 +1,5 @@
+---
+"@primer/css": patch
+---
+
+Update bg deprecations

docs/content/support/v18-migration.mdx

@@ -62,13 +62,13 @@ See [color utility classes](/utilities/colors) for a list of all the functional
 | `.color-bg-primary`         | `.color-bg-default`            |
 | `.color-bg-secondary`       | `.color-bg-subtle`             |
 | `.color-bg-tertiary`        | `.color-bg-subtle`             |
-| `.color-bg-info`            | `.color-bg-accent-subtle`      |
+| `.color-bg-info`            | `.color-bg-accent`             |
 | `.color-bg-info-inverse`    | `.color-bg-accent-emphasis`    |
-| `.color-bg-danger`          | `.color-bg-danger-subtle`      |
+| `.color-bg-danger`          | `.color-bg-danger`             |
 | `.color-bg-danger-inverse`  | `.color-bg-danger-emphasis`    |
-| `.color-bg-success`         | `.color-bg-success-subtle`     |
+| `.color-bg-success`         | `.color-bg-success`            |
 | `.color-bg-success-inverse` | `.color-bg-success-emphasis`   |
-| `.color-bg-warning`         | `.color-bg-attention-subtle`   |
+| `.color-bg-warning`         | `.color-bg-attention`          |
 | `.color-bg-warning-inverse` | `.color-bg-attention-emphasis` |
 
 ## Misc

src/deprecations.json

@@ -28,13 +28,13 @@
     "color-bg-primary": "color-bg-default",
     "color-bg-secondary": "color-bg-subtle",
     "color-bg-tertiary": "color-bg-subtle",
-    "color-bg-info": "color-bg-accent-subtle",
+    "color-bg-info": "color-bg-accent",
     "color-bg-info-inverse": "color-bg-accent-emphasis",
-    "color-bg-danger": "color-bg-danger-subtle",
+    "color-bg-danger": "color-bg-danger",
     "color-bg-danger-inverse": "color-bg-danger-emphasis",
-    "color-bg-success": "color-bg-success-subtle",
+    "color-bg-success": "color-bg-success",
     "color-bg-success-inverse": "color-bg-success-emphasis",
-    "color-bg-warning": "color-bg-attention-subtle",
+    "color-bg-warning": "color-bg-attention",
     "color-bg-warning-inverse": "color-bg-attention-emphasis",
     "text-inherit": "color-fg-inherit",
     "centered": "mx-auto",