tests: requirements with VCS -- docs

Signed-off-by: Jan Kowalleck <jan.kowalleck@gmail.com>

tests/_data/infiles/requirements/with-urls.txt

@@ -1,6 +1,6 @@
 # dependencies from urls
 
-## VCS
+## VCS -- https://pip.pypa.io/en/stable/topics/vcs-support/
 ### commit hash
 git+https://github.com/path/to/package-one@41b95ec#egg=package-one
 ### master branch
@@ -9,7 +9,7 @@ git+https://github.com/path/to/package-two@master#egg=package-two
 git+https://github.com/path/to/package-three@0.1#egg=package-three
 ### release tag
 git+https://github.com/path/to/package-four@releases/tag/v3.7.1#egg=package-four
-### node id
+### complete node id
 git+https://github.com/containerbuildsystem/osbs-client@2bd03f4e0e5edc474b6236c5c128620d988f79a3#egg=package-five