Update page.rst

Absolute path to the extensions.
Merge pull request #507 from barseghyanartur/patch-1

Update page.rst
Fix #511: UnicodeDecodeError if subpage not found
FeinCMS v1.9.3
Merge commit '6726468d1ff85e7b6f6acc88ad993518cc998aad'

* commit '6726468d1ff85e7b6f6acc88ad993518cc998aad':
  FeinCMS v1.9.3
  Fix #511: UnicodeDecodeError if subpage not found
  Update page.rst