Updates: small file upload size and link post-workshop

[sjspielman]

Two items here:

1) Closes #103

• 1 GB --> 100 MB as the file upload limit. Yay or nay on the tildes?

2) Closes #145

• Link to the post-workshop environments page from workshop resources
• As mentioned in this issue, we could also purge "6 months" from other markdowns where it appears. Let me know what you think during review!

(edit) Bonus 3rd issue! Let's go ahead and close #130 here too. Seemed like we were far enough along to just make this happen now, since the final merge into main will spell check anyways.

[sjspielman]

I made several changes in working-with-your-own-data.md, both in response to review and then I got excitable and did more...

• I updated some links which seemed like they could use a refresh
• I have updated headers to focus on transferring with subsections for uploading & downloading (see screenshot below). I also updated filezilla installation a bit, and added a section for installing packages from github.
• I updated some screenshots - took some new Mac ones that match the current UI, and I resized a bunch that were rendering way too bigly, if you will.
• I changed all the Template: and Specific example to bold to make them stand out a bit more amid all the text.
• I ran the spell check script locally since it's not triggered here anymore, and fixed all the speeling erorrs (went with caps for GitLab in dictionary fyi, since that's how we'll use it if ever, I figured?)

Here's how the TOC looks with the updated headers: