solve Makefile requirement

Makefile

@@ -28,10 +28,10 @@ COQTOP=$(COQBIN)coqtop
 COQDEP=$(COQBIN)coqdep $(DEPFLAGS)
 COQDOC=$(COQBIN)coqdoc -d doc -g -utf8 $(DEPFLAGS)
 
-COQVERSION= 8.8.0
+COQVERSION= 8.7.0 or-else 8.7.1 or-else 8.7.2 or-else 8.8.0
 COQV=$(shell $(COQC) -v)
 ifeq ("$(filter $(COQVERSION),$(COQV))","")
-	$(error FAILURE: You need Coq $(COQVERSION) but you have this version: $(COQV))
+$(error FAILURE: You need Coq $(COQVERSION) but you have this version: $(COQV))
 endif
 
 LIBS_FILES = $(wildcard Libs/*.v)