Updated core

Project: help  64187c4328623fca6c00d2f5c9f659211ee18883

New Help: allow product version = "latest"

To enhance version migration, the most recent Help will be
named "latest" in the URL. Explicit last version X.Y will be
symbolic link to 'latest'. e.g. '6.0' -> 'latest'

*This will allow search engine to always index the same 'latest' URL
*External links always land in 'latest' pages.

Change-Id: I5ffa1d268f71b7ebe75d5d90c62bcd6304507602
Reviewed-on: https://gerrit.libreoffice.org/48848Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
Tested-by: Olivier Hallot <olivier.hallot@libreoffice.org>

helpcontent2 @ 64187c43

-Subproject commit c2ef507d3275257c83558c794b3ebb1385f8a4fa
+Subproject commit 64187c4328623fca6c00d2f5c9f659211ee18883