Made it possible to use (refresh-makefile) in order to refresh an edited makefile on the fly.

README.md

@@ -40,7 +40,7 @@ raco pkg install
 For a versioned archive, give the package name explicitly:
 
 ```text
-raco pkg install --name racket-makefile racket-makefile-0.1.6.zip
+raco pkg install --name racket-makefile racket-makefile-0.1.8.zip
 ```
 
 ## Running targets
@@ -78,6 +78,19 @@ registers the targets. Then use the Interactions window:
 Bare identifiers in `make` are target names, so no quote is needed. For
 example, `(make clean)` selects the target named `clean`.
 
+After editing the makefile, use `refresh-makefile` in the same Interactions
+window to reload the makefile without restarting the Racket process:
+
+```racket
+> (refresh-makefile)
+> (make all)
+```
+
+This works both with `#lang racket-makefile` and with an ordinary `#lang racket`
+makefile that requires `main.rkt`. It is useful when the makefile requires modules
+that are expensive to load. Unchanged required modules can remain instantiated
+while the target definitions from the makefile are registered again.
+
 ## Running Racket tools with `raco`
 
 Use `raco` to invoke a Racket tool from a target without depending on `%PATH%`