reflex: add page (#4884)

pages/common/reflex.md

@@ -0,0 +1,24 @@
+# reflex
+
+> Tool to watch a directory and rerun a command when certain files change.
+> More information: <https://github.com/cespare/reflex>.
+
+- Rebuild with `make` if any file changes:
+
+`reflex make`
+
+- Compile and run Go application if any .go file changes:
+
+`reflex --regex='{{\.go$}}' {{go run .}}`
+
+- Ignore a directory when watching for changes:
+
+`reflex --inverse-regex='{{^dir/}}' {{command}}`
+
+- Run command when reflex starts and restarts on file changes:
+
+`reflex --start-service=true {{command}}`
+
+- Substitute the filename that changed in:
+
+`reflex -- echo {}`