Rename guide to "Drupal User Guide" and remove "8" from the title

Yes we definitely should do that. I did a grep and I think we need to fix the following files:
- guide.txt (where the book title is located)
- understanding-themes has some text that mentions Drupal 8

There are also a lot of URLs with 8 in the URL or 8 in the page title. Many of these pages have been edited and the URLs updated to remove the 8. We have a testurls.php script that can be used to see if URLs are 404 or redirected. I think we should run this in a week or so (some updates are in progress on #3133569: Migrate Drupal 8 & 9 documentation to evergreen format (instead of major version specific) ... there should be a nearly 1-to-1 correspondence between the URLs having an 8 that is redirected, and the page titles changing.

Actually maybe that script could be updated to look at the page title of the page you land on and see if that has changed. I can look into that.

Sigh. That script doesn't work any more, because drupal.org has some script-bashing code in place that makes most URLs return a 403 when accessed from a script at that speed. Also, before it decided I was an attacker, it looked like the 8s are still in the URLs, so if we're able to run that at some point, we would need to wait until the URLs with 8 in them are bulk updated on that other issue.

I was also locked out of drupal.org for a bit, but that has been fixed. Anyway, I guess we cannot really use that script; I'll put a note at the top of it.

I talked with @drumm on Slack, and I can get the script temporarily whitelisted at some point. I don't think the URLs have been updated yet.

Is the issue should be fixed after release?

Not sure what you're asking... We should go ahead and fix this once the URLs on drupal.org have been fixed, or we could make a patch for the title and the text in understanding-themes.txt now and do the URLs a little later.

Here's a patch for the part that fixes the guide title and understanding-themes.txt in English.

The URLs and page titles for the drupal.org pages will be more work...

I did a quick grep, and it looks like there are 159 www.drupal.org URLs that should be looked at to see if they have been redirected or their titles have changed. A few are pages like /documentation that will be quick (didn't change)... I'll see what I can do.

It seems like going through these manually is the best option. I found:
- Some links that were easy to fix -- page titles and/or URLs had changed.
- Some URLs that still had /docs/8 on them on drupal.org -- easily fixed by editing the page, checking "automatic alias", and saving (sometimes you have to go up the hierarchy 1 level to get this to work). Then update the User Guide with the new correct URL.
- A couple of links in Additional Resources that were totally useless (removed them).
- A few links whose text didn't follow our standard format of saying "drupal.org community documentation page xyz" -- fixed those.

Here's a patch for the first part of that urls.txt file -- through the install-dev-making file. More to do... probably later this week.
Note: This patch does not include the 2-line patch earlier uploaded.

OK, here's a patch that:
- Fixes the guide title
- Fixes other mentions of 8 in the text
- Fixes drupal.org documentation URLs and page titles so they all match what is currently on drupal.org
- Makes sure all documentation pages are referenced in the standard way
- In one case, removes an "additional resources" page reference that has no useful information in it

There are still some problems, like additional resources references leading you to outdated or Drupal 7 documentation, but I did not address those.

Here's a related issue about Drupal 9 compliance.

Thanks for the careful review!

On item 1, I don't think we really need to link to a page about how to add regions to a theme, since we are not covering theming in the guide right now? The original reference was "Assigning content to regions" (about block placement)... I didn't think it was at all useful as an additional resource for that page.

item 2 -- does look like the formatting is off. Good catch!

item 3 -- +1 on removing pages that have no additional information

I can make a new patch sometime later...

OK here's a new patch with those two changes for items 2/3 of #15.

If we get this patch in, I think we should make a new release for 8.x-8.x (if it still builds OK) and get this deployed to drupal.org, although there are commits coming in from other languages lately, so the build could have problems. I believe drumm has the build running on a test server on a regular basis, so he should be able to tell before we launch an actual deploy or make a release whether it's working or not, if whoever commits this doesn't have the tool chain working. We should also consider making new ebooks.

The next task would be to work on 9.0... for that the first step is usually to run the tests, but I can't do that until
#3147404: Replace mentions of Mayo theme in User Guide
is taken care of.

Sorry, this comment is a bit off-topic for this issue. :)

Patch committed. I'll email the list.

I also (finally) made an 8.x-8.0 release of the User Guide, and uploaded new e-books to https://www.drupal.org/docs/understanding-drupal/user-guide-e-book-downl... -- so I think that closes out the 8.x-8.x branch and we can move on to 9.0.

Given that d.o is moving to semantic versioning, I think we can make the new branch be 9.0.x, corresponding with Drupal Core 9.0.x.

Maybe better to use 9.x branch, it expects just 3 releases before 10, and not a lot of changes.
9.x.y numbering is supposed that something will be backported from later branches, not sure it's a case for user guide

Generally there are small UI changes between minor versions of Drupal. So we have traditionally had a new branch of the User Guide for each minor version of Drupal, because screenshots and text often have to change.