docs: fix typo in path to vendored.txt

docs/developer-guide.txt

@@ -145,5 +145,5 @@ setuptools from source. Eventually, this limitation may be lifted as
 PEP 517/518 reach ubiquitous adoption, but for now, Setuptools
 cannot declare dependencies other than through
 ``setuptools/_vendor/vendored.txt`` and
-``pkg_reosurces/_vendor/vendored.txt`` and refreshed by way of
+``pkg_resources/_vendor/vendored.txt`` and refreshed by way of
 ``paver update_vendored`` (pavement.py).