Update docs for archive site modifications (apache#56764)

Refreshed and clarified docs after running historical site modification
update (remove Airflow Summit header).

Related: apache/airflow-site-archive#23
Related: apache/airflow-site-archive#24

Author: potiuk

docs/README.md

@@ -210,20 +210,24 @@ bad links or when we change some of the structure in the documentation. This can
    text editor, script, etc. Those files are generated as `html` files and are not meant to be regenerated,
    they should be modified as `html` files in-place
 3. Commit the changes to `airflow-site-archive` repository and push them to `some` branch of the repository.
-4. Run `Sync GitHub to S3` workflow in `airflow-site-archive` repository. This will upload the modified
-   documentation to the S3 bucket.
-5. You can choose whether to sync the changes to `live` or `staging` bucket. The default is `live`.
+4. Create a Pull Request from that branch and merge it to `main`
+5. Run `Sync GitHub to S3` workflow in `airflow-site-archive` repository. This will upload the modified
+   documentation to the S3 bucket. Use `main` branch (default) as "Reference of the commit used
+   for synchronization". You can choose whether to sync the changes to `live` or `staging` bucket.
+   The default is `live`:
+   ![Sync GitHub to S3](images/sync_github_to_s3.png)
 6. By default, the workflow will synchronize all documentation modified in a single last commit pushed to
-   the branch you specified. You can also specify "full_sync" to synchronize all files in the repository.
-7. In case you specify "full_sync", you can also synchronize `all` docs or only selected documentation
+   the `main`. You can also specify `full_sync` to synchronize all files in the repository if you want to
+   make sure that S3 reflects `main`. The workflow might run for a long time (hours) in case of full sync
+   or many changes to the `.html` files.
+7. In case you specify `full_sync`, you can also synchronize `all` docs or only selected documentation
    packages (for example `apache-airflow` or `docker-stack` or `amazon` or `helm-chart`) - you can specify
-   more than one package separated by  spaces.
-8. After you synchronize the changes to S3, the Sync `S3 to GitHub` workflow will be triggered
-   automatically, and the changes will be synchronized to `airflow-site-archive` `main` branch - so there
-   is no need to merge your changes to `main` branch of `airflow-site-archive` repository. You can safely
-   delete the branch you created in step 3.
-
-![Sync GitHub to S3](images/sync_github_to_s3.png)
+   more than one package separated by spaces.
+8. The workflow will invalidate Cloudflare cache for "live" or "staging" bucket respectively.
+9. Run the "Build docs" workflow in `airflow-site` repository to make sure that Fastly cache of the
+   https://airflow.apache.org or https://airflow.staged.apache.org/ invalidated. Use `main` to rebuild site
+   for `live` site and `staging` to rebuild the `staging` site:
+   ![Build docs](images/build-docs.png)
 
 
 ## Manually publishing documentation directly to S3