docs: updated image and added link in how-to-translate.md

- In this screen preferably click on `Unstranslated strings` and `Unfinished strings`. If there aren't any you can select `Strings waiting for review`. You can also use the `Search` tab to look for a specific string you want to edit.

- The next screen is where you will be working

- In the box on top labelled 'Translation' you can see words in English in one text box and below you will see another text box where you need to type the translation in the language you are working on:

![Translate](images/Weblate_Translate.png)

![Translate](images/Weblate_Translate_Page.png)

- Once you have translated the string, click 'Save and continue' to move to the next string. Please keep the default `Waiting for review` option selected.

- The next string will show up for you to translate