Adding Kapa Assistant to Docs (#5290)

## What type of PR is this? (check all applicable)

- [ ] Refactor
- [ ] Feature
- [ ] Bug Fix
- [ ] Optimization
- [ x ] Documentation Update
- [ ] Community Node Submission


## Have you discussed this change with the InvokeAI team?
- [ x ] Yes
- [ ] No, because:

      
## Have you updated all relevant documentation?
- [ x ] Yes
- [ ] No


## Description
This adds the Kapa assistant to our docs.

docs/javascripts/init_kapa_widget.js

@@ -0,0 +1,10 @@
+document.addEventListener("DOMContentLoaded", function () {
+  var script = document.createElement("script");
+  script.src = "https://widget.kapa.ai/kapa-widget.bundle.js";
+  script.setAttribute("data-website-id", "b5973bb1-476b-451e-8cf4-98de86745a10");
+  script.setAttribute("data-project-name", "Invoke.AI");
+  script.setAttribute("data-project-color", "#11213C");
+  script.setAttribute("data-project-logo", "https://avatars.githubusercontent.com/u/113954515?s=280&v=4");
+  script.async = true;
+  document.head.appendChild(script);
+});

mkdocs.yml

@@ -101,6 +101,8 @@ plugins:
 extra_javascript:
   - https://unpkg.com/tablesort@5.3.0/dist/tablesort.min.js
   - javascripts/tablesort.js
+  - https://widget.kapa.ai/kapa-widget.bundle.js
+  - javascript/init_kapa_widget.js
 
 extra:
   analytics: