Jim Winstead

Integration test won't pass in CI because it requires simultaneous changes from php/doc-base#147

Okay, PR is just a clean set of changes to versions now. [The change to extension-membership for the MongoDB books](https://github.com/php/doc-en/pull/3672/commits/a51ebd074abdc1cd18ef9da1628d6d5049616562) was already cherry-picked and pushed into master.

Maybe leave the xi:include in a comment and mention that once whatever tool in the process that needs to add XInclude support does, this section can be fixed?

A breadcrumb for anyone interested in the future: it's `libxml2` that lacks XInclude 1.1 support, the spec is 8 years old, and the open issue for adding support in `libxml2`...

@haszi Looks great, thanks!

This doesn't get rid of the reference to that section as #1059 does.

This is only needed for php/doc-en#1674, so pending decision on whether it's okay to mention another 3rd-party non-open-source package system.

A common theme in the user-contributed notes for `hash()` was performance benchmarks, so it's probably worth adding some discussion of that (including why you may not even want the _fastest_...

@cmb69, I thought that was a good starting point for beefing up the introduction to the documentation for the hash extension! PR is just a draft, feel free to suggest...

Related to #108.