Typo fix Update flags.mk (#13226)

just/flags.mk

@@ -7,7 +7,7 @@
 #
 # MAKEFLAGS is a string of the form:
 # "abc --foo --bar=baz -- VAR1=val1 VAR2=val2", namely:
-# - abc is the concatnation of all short flags
+# - abc is the concatenation of all short flags
 # - --foo and --bar=baz are long options,
 # - -- is the separator between flags and variable assignments,
 # - VAR1=val1 and VAR2=val2 are variable assignments
@@ -21,4 +21,4 @@
 tmp-flags := $(wordlist 2,$(words $(MAKEFLAGS)),$(MAKEFLAGS))
 # Then remove all long options, including the -- separator, if needed. That
 # leaves only variable assignments.
-JUSTFLAGS := $(patsubst --%,,$(tmp-flags))
\ No newline at end of file
+JUSTFLAGS := $(patsubst --%,,$(tmp-flags))