xcowsay: add page (#6974)

pages/linux/xcowsay.md

@@ -0,0 +1,29 @@
+# xcowsay
+
+> Display a cute cow and message on your Linux desktop.
+> The cow is displayed for either a fixed amount of time, or an amount of time calculated from the size of the text. Click on the cow to dismiss it immediately.
+> More information: <https://www.doof.me.uk/xcowsay/>.
+
+- Display a cow saying "hello, world":
+
+`xcowsay "{{hello, world}}"`
+
+- Display a cow with output from another command:
+
+`ls | xcowsay`
+
+- Display a cow at the specified X and Y coordinates:
+
+`xcowsay --at={{X}},{{Y}}`
+
+- Display a different sized cow:
+
+`xcowsay --cow-size={{small|med|large}}`
+
+- Display a thought bubble instead of a speech bubble:
+
+`xcowsay --think`
+
+- Display a different image instead of the default cow:
+
+`xcowsay --image={{path/to/file}}`