Refactor screenshots to code blocks and fix step numbering (closes #210)

[avinab-neogy]

This PR addresses the following:

1. In tutorials/running_r, substituted the last screenshot with an equivalent R code example using an Rconsole fenced block.

2. Fixed step numbering for the local setup section to ensure proper sequence.

3. Updated screengrabs and instructions for running R in the tutorial to reflect feedback.

4. All requested changes from the previous PR comments have been incorporated in this PR.

closes #210

[hturner]

The formatting is much better now. However the screenshots need improving.

• rdev4.png: text is too small
• rdev11.png: container should not be connected to git, so we should not see information about git commits/PRs in the footer ("Neil Shephard (10 months ago)" should not be there).
• rdev12.png: version of R should be much more recent than this. When I run the codespace from the devel branch on GitHub codespaces it comes with R 4.5.1.
• rdev5.png: text too small again. Try to avoid a layout that shows local file paths.

Best would be to use GitHub Codespaces to take the screenshots (without dark mode set) as that is the default way to use the Dev Container and avoids any issues with your local setup.

Use Ctrl + = (or your browser Zoom controls) to zoom the full view. The text in the screenshots should end up about the same size as the normal text in the website.

[avinab-neogy]

Hi @hturner
I have opened a new PR to address this #275 .
Closing this PR.
Thanks!