Starter documentation and snippet fixes

Author: jonniebigodes

code/addons/docs/docs/theming.md

@@ -44,7 +44,7 @@ The classes correspond to markdown elements (e.g. `sbdocs-title`, `sbdocs-subtit
 
 You can style these classes in `.storybook/preview-head.html`. For example, here's how to make the content wider for UHD displays:
 
-```html
+```html title=".storybook/preview-head.html"
 <style>
   .sbdocs.sbdocs-content {
     max-width: 1440px;

docs/_assets/contribute/local-storybook-website-dropdown-optimized.mp4

@@ -91,4 +91,3 @@ const meta: Meta {
 
 export default meta;
 ```
-

docs/_assets/contribute/local-storybook-website-dropdown-optimized.png

@@ -131,4 +131,3 @@ const meta: Meta = {
 
 export default meta;
 ```
-

docs/_snippets/add-localize-package-to-polyfills.md

@@ -38,4 +38,3 @@ const ExampleToolbar = () => {
   );
 };
 ```
-

docs/_snippets/addon-actions-action-function.md

@@ -38,4 +38,3 @@ const ThemePanel = (props) => {
   );
 };
 ```
-

docs/_snippets/addon-backgrounds-grid.md

@@ -240,4 +240,3 @@ export const ResetHighlight: Story = {
   ],
 };
 ```
-

docs/_snippets/addon-consume-and-update-globaltype.md

@@ -1,4 +1,4 @@
-```shell renderer="common" language="js" packageManager="npx"
+```shell renderer="common" language="js" packageManager="npm"
 npx storybook add @storybook/experimental-addon-test
 ```