Fix/copy improvements (#16859)

* fix(seed): Simplify copy of lessons and remove need for image

* rework copy for account creation and login emails

* fix: Fixup email template and lock-file

challenges/04-data-visualization/data-visualization-with-d3.json

@@ -9,8 +9,8 @@
       "title": "Introduction to the Data Visualization with D3 Challenges",
       "description": [
         [
-          "http://imgs.xkcd.com/comics/movie_narrative_charts.png",
-          "XKCD web comic showing very detailed charts of movie character interactions for Lord of the Rings, Star Wars (original trilogy), Jurassic Park, 12 Angry Men, and Primer. The charts show grouped lines, representing when characters appear together, over time.",
+          "",
+          "",
           "D3.js, or D3, stands for Data Driven Documents. D3 is a JavaScript library to create dynamic and interactive data visualizations in the browser. It's built to work with common web standards, namely HTML, CSS, and Scalable Vector Graphics (SVG).<br><br>D3 takes input data and maps it into a visual representation of that data. It supports many different data formats. D3 lets you bind (or attach) the data to the Document Object Model (DOM). You use HTML or SVG elements with D3's built-in methods to transform the data into a visualization.<br><br>D3 gives you a lot of control over the presentation of data. This section covers the basic functionality and how to create visualizations with the D3 library.",
           ""
         ]

challenges/04-data-visualization/json-apis-and-ajax.json

@@ -14,8 +14,8 @@
       "title": "Introduction to the JSON APIs and AJAX Challenges",
       "description": [
         [
-          "http://imgs.xkcd.com/comics/api.png",
-          "XKCD web comic with a user sitting at a computer reading the instructions for an API Guide for a site. The text below notes \"If you do things right, it can take people awhile to realize that your 'API documentation' is just instructions for how to look at your website.\"",
+          "",
+          "",
           "Similar to how User Interfaces help people use programs, Application Programming Interfaces (APIs) help programs interact with other programs. APIs are tools that computers use to communicate with one another, in part to send and receive data. You can use API functionality in your page once you understand how to make requests and process data from it. Programmers often use AJAX technologies when working with APIs.<br><br>The term AJAX originated as an acronym for Asynchronous JavaScript And XML. It refers to a group of technologies that make asynchronous requests to a server to transfer data, then load any returned data into the page. An asynchronous process has a couple key properties. The browser does not stop loading a page to wait for the server's response. Also, the browser inserts updated data into part of the page without having to refresh the entire page.<br><br>User experience benefits from asynchronous processes in several ways. Pages load faster since the browser isn't waiting for the server to respond in the middle of a page render. Requests and transfers happen in the background, without interrupting what the user is doing. When the browser receives new data, only the necessary area of the page refreshes. These qualities especially enhance the user experience for single page applications.<br><br>The data transferred between the browser and server is often in a format called JavaScript Object Notation (JSON). JSON resembles JavaScript object literal syntax, except that it's transferred as a string. Once received, it can be converted into an object and used in a script.<br><br>This section covers how to transfer and use data using AJAX technologies with a freeCodeCamp API.",
           ""
         ]