:book: start Repl doc

diff --git a/plug b/plug
index a808acc3bd3144b5c80011e4b28faf7438361462..4387f4fe3ac0326476225fa6190dc428e3303f41 160000 (submodule)
--- a/plug
+++ b/plug
@@ -1 +1 @@
-Subproject commit a808acc3bd3144b5c80011e4b28faf7438361462
+Subproject commit 4387f4fe3ac0326476225fa6190dc428e3303f41