Fix release doc workflow

[MrSebastian]

Description:

• fix working dir
• fix publish dir

Reference:

Definition of Done (DoD):

• success verified via manual run of workflow https://github.com/it-at-m/Praktikumsplaner/actions/runs/9060414230/job/24890050649

[MrSebastian]

the github-page is up to date, because of the manual triggered build: https://it-at-m.github.io/Praktikumsplaner