docs: Add primary artist extraction examples for scrobble modification

docsite/docs/configuration/transforms.mdx

@@ -479,3 +479,41 @@ Removes the phrase `(Album Version)` from the Title of a Play
 }
 ```
 </details>
+
+### Extract primary Artist from delimited, multi-Artist string
+
+When the Artist string is actually a multi-artist, delimited string, this search-and-replace will replace the string with just the first artist found.
+
+Ex
+
+```
+My Artist One / My Artist Two / Another Guy
+My Artist One
+```
+
+Artists are delimited with a spaced forward slash (`/`) in the regex below. Replace the contents of the `delim` capture group with the delimiter for your use case. Some more common scenarios:
+
+* `(?<delim>\\/)` No spaces between slash IE `My Artist One/My Artist Two/Another Guy`
+* `(?<delim>\\s*\\\\\s*)` Backslash instead of forward slash IE `My Artist One \ My Artist Two \ Another Guy`
+* `(?<delim>,)` Comma IE `My Artist One, My Artist Two, Another Guy`
+
+<details>
+
+    <summary>Example</summary>
+```json5 title="config.json"
+{
+  "sourceDefaults": {
+    "playTransform": {
+      "preCompare": {
+        "artists": [
+          {
+            "search": "(.*?)(?<delim>\\s*\\/\\s*)(.*$)",
+            "replace": "$1"
+          }
+        ]
+      }
+    }
+  }
+}
+```
+</details>