Changes

Changes from Mercurial (hg https://foss.heptapod.net/isa-afp/afp-devel/ default)

Re-activated index generation.
Added subcaption.sty to overwrite the version provided by TexLive 2021 on Ubuntu 22.04.

Changeset 14421:e2770d242c9b by achim d. brucker _adbrucker@0x5f.org_: Re-activated index generation.
The file was modified	`thys/Isabelle_DOF/document/preamble.tex`
Changeset 14420:a1b828a45d00 by achim d. brucker _adbrucker@0x5f.org_: Added subcaption.sty to overwrite the version provided by TexLive 2021 on Ubuntu 22.04.
The file was added	`thys/Isabelle_DOF/document/subcaption.sty`
The file was modified	`thys/Isabelle_DOF/ROOT`