Document remote justfile workaround (#2175)

README.md

@@ -3668,6 +3668,22 @@ ls:
     echo '{{absolute_path(".")}}'
 ```
 
+### Remote Justfiles
+
+If you wish to include a `mod` or `import` source file in many `justfiles`
+without needing to duplicate it, you can use an optional `mod` or `import`,
+along with a recipe to fetch the module source:
+
+```just
+import? 'foo.just'
+
+fetch:
+  curl https://raw.githubusercontent.com/casey/just/master/justfile > foo.just
+```
+
+Given the above `justfile`, after running `just fetch`, the recipes in
+`foo.just` will be available.
+
 ### Alternatives and Prior Art
 
 There is no shortage of command runners! Some more or less similar alternatives