vf: add page (#11219)

Co-authored-by: Lena <126529524+acuteenvy@users.noreply.github.com>

pages/common/vf.md

@@ -0,0 +1,36 @@
+# vf
+
+> VirtualFish is a fish shell tool for managing Python virtual environments.
+> More information: <https://virtualfish.readthedocs.io/en/latest/>.
+
+- Create a virtual environment:
+
+`vf new {{virtualenv_name}}`
+
+- Create a virtual environment for a specific Python version:
+
+`vf new --python {{/usr/local/bin/python3.8}} {{virtualenv_name}}`
+
+- Activate and use the specified virtual environment:
+
+`vf activate {{virtualenv_name}}`
+
+- Connect the current virtualenv to the current directory, so that it is activated automatically as soon as you enter it (and deactivated as soon as you leave):
+
+`vf connect`
+
+- Deactivate the current virtual environment:
+
+`vf deactivate`
+
+- List all virtual environments:
+
+`vf ls`
+
+- Remove a virtual environment:
+
+`vf rm {{virtualenv_name}}`
+
+- Display help:
+
+`vf help`