Cleanup blocked pages

Author: Archmonger

docs/src/learn/add-react-to-an-existing-project.md

@@ -4,6 +4,7 @@
 
     See [this issue](https://github.com/reactive-python/reactpy/issues/653) for more details.
 
+<!--
 ## Overview
 
 <p class="intro" markdown>
@@ -12,7 +13,6 @@ If you want to add some interactivity to your existing project, you don't have t
 
 </p>
 
-<!--
 <Note>
 
 **You need to install [Node.js](https://nodejs.org/en/) for local development.** Although you can [try React](/learn/installation#try-react) online or with a simple HTML page, realistically most JavaScript tooling you'll want to use for development requires Node.js.

docs/src/learn/extra-tools-and-packages.md

@@ -0,0 +1,2 @@
+- ReactPy Router
+- ReactPy Flake8

docs/src/learn/python-in-psx-with-curly-braces.md

@@ -4,6 +4,7 @@
 
     See [this issue](https://github.com/reactive-python/reactpy/issues/918) for more details.
 
+<!--
 ## Overview
 
 <p class="intro" markdown>
@@ -19,7 +20,6 @@ JSX lets you write HTML-like markup inside a JavaScript file, keeping rendering
     -   How to call a JavaScript function inside JSX with curly braces
     -   How to use a JavaScript object inside JSX with curly braces
 
-<!--
 ## Passing strings with quotes
 
 When you want to pass a string attribute to JSX, you put it in single or double quotes:

docs/src/learn/react-developer-tools.md

@@ -4,6 +4,7 @@
 
     See [this issue](https://github.com/reactive-python/reactpy/issues/1072) for more details.
 
+<!--
 ## Overview
 
 <p class="intro" markdown>
@@ -16,7 +17,7 @@ Use React Developer Tools to inspect React [components](../learn/your-first-comp
 
     -   How to install ReactPy Developer Tools
 
-<!--
+
 ## Browser extension
 
 The easiest way to debug websites built with React is to install the React Developer Tools browser extension. It is available for several popular browsers:

docs/src/learn/writing-markup-with-psx.md

@@ -4,7 +4,7 @@
 
     See [this issue](https://github.com/reactive-python/reactpy/issues/918) for more details.
 
-## Overview
+<!-- ## Overview
 
 <p class="intro" markdown>
 
@@ -20,14 +20,15 @@ _PSX_ is a syntax extension for JavaScript that lets you write HTML-like markup
 
 ## PSX: Putting markup into Python
 
-The Web has been built on HTML, CSS, and JavaScript. For many years, web developers kept content in HTML, design in CSS, and logic in JavaScript—often in separate files! Content was marked up inside HTML while the page's logic lived separately in JavaScript:
+The Web has been built on HTML, CSS, and JavaScript. For many years, web developers kept content in HTML, design in CSS, and logic in JavaScript—often in separate files! Content was marked up inside HTML while the page's logic lived separately in JavaScript: -->
 
 <!-- TODO: Diagram -->
 
-But as the Web became more interactive, logic increasingly determined content. Scripting languages are now in charge of the HTML! This is why **in React, rendering logic and markup live together in the same place—components.**
+<!-- But as the Web became more interactive, logic increasingly determined content. Scripting languages are now in charge of the HTML! This is why **in React, rendering logic and markup live together in the same place—components.** -->
 
 <!-- TODO: Diagram -->
 
+<!--
 Keeping a button's rendering logic and markup together ensures that they stay in sync with each other on every edit. Conversely, details that are unrelated, such as the button's markup and a sidebar's markup, are isolated from each other, making it safer to change either of them on their own.
 
 Each React component is a JavaScript function that may contain some markup that React renders into the browser. React components use a syntax extension called PSX to represent that markup. PSX looks a lot like HTML, but it is a bit stricter and can display dynamic information. The best way to understand this is to convert some HTML markup to PSX markup.
@@ -36,7 +37,7 @@ Each React component is a JavaScript function that may contain some markup that
 
     PSX and ReactPy are two separate things. They're often used together, but you _can_ use them independently of each other. PSX is a syntax extension, while ReactPy is a Python library.
 
-<!-- ## Converting HTML to PSX
+ ## Converting HTML to PSX
 
 Suppose that you have some (perfectly valid) HTML:
 

mkdocs.yml

@@ -12,7 +12,7 @@ nav:
                 - Add React to an Existing Project 🚫: learn/add-react-to-an-existing-project.md
                 - Editor Setup: learn/editor-setup.md
                 - React Developer Tools 🚫: learn/react-developer-tools.md
-                - Installable Extras: learn/installable-extras.md
+                - Extra Tools and Packages 🚧: learn/extra-tools-and-packages.md
           - More Tutorials:
                 - "Tutorial: React Bootstrap 🚫": learn/tutorial-react-bootstrap.md
                 - "Tutorial: Material UI 🚫": learn/tutorial-material-ui.md