🚀 MVP launch buttons for JupyterHub & MyBinder (#503)

* wip: initial prototype

* fix: drop unused deps

* fix: improve style

* wip: jhub launcher

* wip: link building

* chore: refactoring

* feat: use form

* feat: enable copy-to-clipboard

* feat: add launch icon

* refactor: use state rather than refs

* refactor: move to LaunchButton.tsx

* fix: don't store invalid link in clip

* fix: use project frontmatter

* chore: revert style changes

* fix: just export types for now

* fix: import type

* refactor: use project config

* fix: bugfixes

* fix: small style fixes

* docs: update README

* fix: styling

README.md

@@ -91,15 +91,25 @@ To interact with the themes in development mode (e.g. with live-reload of compon
 2. the renderer/application (theme)
 3. a process watching all components
 
+First, start the theme application:
 ```bash
-# In a directory with content
-myst start --headless
-# In myst-theme
+# Install dependencies
+npm install
+# First, build the theme
+npm run build
+
+# Then start the theme
 npm run theme:book
 # In another terminal, watch for changes and rebuild
 npm run dev
 ```
 
+Then, start the content server application in e.g. the mystmd docs:
+```bash
+# In a directory with content
+myst start --headless
+```
+
 > **Note**: in the future, this repository will likely have it's own content to test out with the themes.
 > You can currently look to the mystjs/docs folder, or an [article](https://github.com/simpeg/tle-finitevolume) or a [thesis](https://github.com/rowanc1/phd-thesis).