This commit adds the last sequence number and primary term of the last operation that have
modified a document to `GetResult` and uses it to power the Update API.
Relates #36148
Relates #10708
* Replace custom type names with _doc in REST examples.
* Avoid using two mapping types in the percolator docs.
* Rename doc -> _doc in the main repository README.
* Also replace some custom type names in the HLRC docs.
and be much more stingy about what we consider a console candidate.
* Add `// CONSOLE` to check-running
* Fix version in some snippets
* Mark groovy snippets as groovy
* Fix versions in plugins
* Fix language marker errors
* Fix language parsing in snippets
This adds support for snippets who's language is written like
`[source, txt]` and `["source","js",subs="attributes,callouts"]`.
This also makes language required for snippets which is nice because
then we can be sure we can grep for snippets in a particular language.
We have 1074 snippets that look like they should be converted to
`// CONSOLE`. At least that is what `gradle docs:listConsoleCandidates`
says. This adds `// NOTCONSOLE` to explicitly mark snippets that
*shouldn't* be converted to `// CONSOLE`. After marking the blindingly
obvious ones this cuts the remaining snippet count to 1032.