Fix typos and improve code snippets in chapter 7

[pBouillon]

Hi, I noticed some things that could have been improved there:

• There was a small typo in a paragraph (Let;s)
• The examples had the path of the file as a raw parameter instead of taking advantage of Docusaurus text blocks
• A template was containing a strange closing tag

I hope that this will help!

I am also willing to change other code examples to use the Docusaurus file location instead of the comments spread here and there