updates moonriver 3100 runtime

[dawnkelly09]

Description

• updates spec_version for moonriver in variables.yml
• updates needed GH repo links for code pointers (I only found one)
• updates runtime by blocks page to add moonriver block # and link to the first 3100 block

Checklist

• [ x ] I have added a label to this PR 🏷️
• [ ] I have run my changes through Grammarly
• [ ] If this requires translations for the moonbeam-docs-cn repo, I have created a ticket for the translations in Jira
• [ ] If pages have been moved around, I have created an additional PR in moonbeam-mkdocs to update redirects
• [ ] If pages have been moved around, I have run the move-pages.py script to move the pages and update the image paths on the chinese repo
  • [ ] After the script has been run, I have created an additional PR in moonbeam-docs-cn
• [ ] If images have been added, I have run the compress-images.py script to compress the images.
• [ ] If variables (in variables.yml) need to be updated (such as a name change), I have updated the moonbeam-docs-cn repo to use the new variables
• [ ] If this page requires a disclaimer, I have added one

Corresponding PRs

Will open separate PR for the moonbeam-docs-test-suite repo update

After Translation Requirements

• [ ] Will need to create PR in moonbeam-docs repo to remove images
• [ ] Will need to create PR in moonbeam-docs repo to remove variables
• [ ] Will need to create PR in moonbeam-mkdocs repo to add redirects for Chinese site
• [ ] No additional PRs are required after the translations are done

Items to be Updated

Please list any of the items that will need to be added or deleted after the translations are done here.