Add instructions for local deployment

[kabilar]

• [x] Update readme with docker run command for local deployment
• [x] Update gitignore for directories that are created by local deployment

[yarikoptic]

conflicts amassed

re @waxlamp

so someone with more authority on this repo ...

I guess it was not in a "formal" authority way since you are the owner here too

right? with this I also entitle you to the "informal" authority to provide your feedback/approvals on this repo @waxlamp ;)

[satra]

last week github pages wouldn't build because of a bug. it looks like it's been released, and the gemfile should simply contain. this should keep any local dev consistent with github's page build mechanism

gem "github-pages", "=231"

alternatively, one could in the future, switch to actions from pages (https://github.com/sensein/sensein.github.io/blob/main/.github/workflows/pages-build.yml), which i did last week because of the bug. an action also gives more capabilities, like using jekyll 4, if needed.

[satra]

also the Gemfile.lock should be removed and regenerated, based on github-jekyll changes.