index.html missing from solfege-doc

[Hanan Rosemarin]

installing solfege-doc adds help files in /usr/share/solfege/help
however, the program (solfege) expects to find the main index file:
/usr/share/solfege/help/C/index.html

which is not present in the package (or perhaps needs to be generated upon installation)

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: solfege-doc 3.23.4-7
ProcVersionSignature: Ubuntu 5.4.0-81.91-generic 5.4.128
Uname: Linux 5.4.0-81-generic x86_64
NonfreeKernelModules: socwatch2_14 vtsspp sep5 socperf3 pax
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Sun Aug 15 15:47:12 2021
Dependencies:

InstallationDate: Installed on 2019-02-10 (917 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_IL:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_IL
 SHELL=/bin/bash
SourcePackage: solfege
UpgradeStatus: Upgraded to focal on 2020-09-29 (319 days ago)