doc/04-Upgrading.md: Fix path for schema upgrades

[julianbrost]

Looks like these were never in /usr/share/doc and the documentation was just wrong for 1.0.0.

The updated paths match both 1.0.0 release packages and the current snapshot packages:

$ curl -s https://packages.icinga.com/debian/pool/main/i/icingadb/icingadb_1.0.0-1.bullseye_amd64.deb | dpkg --contents - |& grep -F .sql        
-rw-r--r-- root/root     59172 2022-06-29 19:33 ./usr/share/icingadb/schema/mysql/schema.sql
-rw-r--r-- root/root     28474 2022-06-29 19:33 ./usr/share/icingadb/schema/mysql/upgrades/1.0.0-rc2.sql
-rw-r--r-- root/root     12098 2022-06-29 19:33 ./usr/share/icingadb/schema/mysql/upgrades/1.0.0.sql
-rw-r--r-- root/root     93974 2022-06-29 19:33 ./usr/share/icingadb/schema/pgsql/schema.sql

$ curl -s https://packages.icinga.com/fedora/36/release/x86_64/icingadb/icingadb-1.0.0-1.fc36.icinga.x86_64.rpm | rpm -qlp - |& grep -F .sql         
/usr/share/icingadb/schema/mysql/schema.sql
/usr/share/icingadb/schema/mysql/upgrades/1.0.0-rc2.sql
/usr/share/icingadb/schema/mysql/upgrades/1.0.0.sql
/usr/share/icingadb/schema/pgsql/schema.sql

$ curl -s https://packages.icinga.com/debian/pool/main/i/icingadb/icingadb_1.1.0+86.g3f768dd-1691483080+debian11_amd64.deb | dpkg --contents - |& grep -F .sql
-rw-r--r-- root/root     60710 2023-08-08 10:08 ./usr/share/icingadb/schema/mysql/schema.sql
-rw-r--r-- root/root     28474 2023-08-08 10:08 ./usr/share/icingadb/schema/mysql/upgrades/1.0.0-rc2.sql
-rw-r--r-- root/root     12098 2023-08-08 10:08 ./usr/share/icingadb/schema/mysql/upgrades/1.0.0.sql
-rw-r--r-- root/root      2537 2023-08-08 10:08 ./usr/share/icingadb/schema/mysql/upgrades/1.1.1.sql
-rw-r--r-- root/root     95820 2023-08-08 10:08 ./usr/share/icingadb/schema/pgsql/schema.sql
-rw-r--r-- root/root      1915 2023-08-08 10:08 ./usr/share/icingadb/schema/pgsql/upgrades/1.1.1.sql

$ curl -s https://packages.icinga.com/fedora/38/snapshot/x86_64/icingadb/icingadb-1.1.0+86.g3f768dd-1691483080.fc38.x86_64.rpm | rpm -qlp - |& grep -F .sql
/usr/share/icingadb/schema/mysql/schema.sql
/usr/share/icingadb/schema/mysql/upgrades/1.0.0-rc2.sql
/usr/share/icingadb/schema/mysql/upgrades/1.0.0.sql
/usr/share/icingadb/schema/mysql/upgrades/1.1.1.sql
/usr/share/icingadb/schema/pgsql/schema.sql
/usr/share/icingadb/schema/pgsql/upgrades/1.1.1.sql