Tutorial/FAQ updates for 21.09 changes around "Export History to file" function

"History > Export History to file" function had major revisions in the `21.01` release. Related help/usage needs an update (corrected, thanks @mvdbeek)

- [ ] Included in at least one tutorial: https://training.galaxyproject.org/training-material/topics/galaxy-interface/tutorials/download-delete-data/tutorial.html
- [ ] Add both export and import via history archive (link + remote file directory) to FAQs in the "History" section of FAQs
- [ ] Search Galaxy Help and update any prior Q&A about history archives with links to the above FAQs
- [ ] Add in an FAQ help link to Galaxy itself -- to both the export and import function areas. https://github.com/galaxyproject/galaxy/issues/12761