[update docs] Fix syntax error in plugin docs

website/docs/config_guides/customizing_feature_colors.md

@@ -32,7 +32,7 @@ For example, create a file named "myplugin.js" (see also Footnote 1)
   // the plugin will be included in both the main thread and web worker, so
   // install plugin to either window or self (webworker global scope)
   ;(typeof self !== 'undefined' ? self : window).JBrowsePluginMyPlugin = {
-    default: Plugin,
+    default: MyPlugin,
   }
 })()
 ```

website/docs/config_guides/customizing_feature_details.md

@@ -82,7 +82,7 @@ You can make a small plugin file "myplugin.js"
   // the plugin will be included in both the main thread and web worker, so
   // install plugin to either window or self (webworker global scope)
   ;(typeof self !== 'undefined' ? self : window).JBrowsePluginMyPlugin = {
-    default: Plugin,
+    default: MyPlugin,
   }
 })()
 ```
@@ -155,31 +155,45 @@ of your data file, you could make a jexl function such as the following
   // the plugin will be included in both the main thread and web worker, so
   // install plugin to either window or self (webworker global scope)
   ;(typeof self !== 'undefined' ? self : window).JBrowsePluginMyPlugin = {
-    default: Plugin,
+    default: MyPlugin,
   }
 })()
 ```
 
-And then in your config
+And then in your config.json
 
 ```json
 {
-  ...
-  "formatDetails": {
-    "feature": "jexl:{dbxref:linkout(feature)}",
-    "subfeatures": "jexl:{dbxref:linkout(feature)}"
-  }
+  "plugins": [
+    {
+      "name": "MyPlugin",
+      "umdLoc": { "uri": "myplugin.js" }
+    }
+  ],
+  "tracks": [
+    {
+      "trackId": "mytrack",
+      "name":"My track",
+      "adapter": {...},
+      "formatDetails": {
+        "feature": "jexl:{dbxref:linkout(feature)}",
+        "subfeatures": "jexl:{dbxref:linkout(feature)}"
+      }
+    }
+  ]
 }
 ```
 
-#### Footnote 1
+#### Footnote 1 - the feature details are serialized to plain JSON objects
 
 Note that the feature for feature detail panels is different from that in the
 color callback: it is a plain JS object. So instead of `feature.get('start')`,
 you can say just `feature.start`. The reason it is different for the feature
 details callbacks (compared with e.g. the color callbacks) is that the feature
 is serialized into the session.
 
+#### Footnote 2 - why are feature details plain JSON objects when other usages aren't?
+
 You might also ask why aren't all features serialized or plain JSON objects
 normally? Well, some feature types like alignments features benefit from only
 being partially serialized e.g. getting only a couple attributes via