use relative path to page
minor #4132 Use proper way to reference a doc page for legacy sessions (Baptouuuu)

This PR was submitted for the 2.5 branch but it was merged into the 2.3 branch instead (closes #4132).

Discussion
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Use proper way to reference a doc page for legacy sessions

| Q                  | A
| ---------------- | ---
| Doc fix?        | yes
| New docs?   | no
| Applies to     | 2.5+
| Fixed tickets |

Commits
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ec04c2a use relative path to page