Added HTML examples for tables and lists

[anenadic]

This PR addresses #210. The changes include:

• adding HTML table and list tags to the callout with all the HTML tags in the introduction episode (given that they are mainly used in the following examples throughout the rest of the lesson)
• slightly modified layout of the above callout - it now renders as a list to aid readability
• adding HTML table and list example snippets below the basic "Hello, World!" example (to draw people's attention to these two specific tags as we will use tables and lists in the following examples throughout the rest of the lesson)
• replacing the HTML table example with simple Markdown list in "Arrays"/"Loops and Collections" episode because it is simpler and won't add cognitive overload to explaining for loops
• a few more small typo fixes spotted throughout

[anenadic]

Nice one @unode, thank you for the review and improvements!