use em dash, spelling fix

README.md

@@ -55,6 +55,6 @@ do not inadvertently produce unintended results.
 By submitting your module to the ecosystem, you agree that all entities involved in the operation of the ecosystem,
 including its testing, mirroring, or archiving, as well as any package installers and auxiliary tools,
 are allowed to copy, distribute, and modify your META file without limitation for the
-purposes of making your module available to the Perl 6 community—-regardless of what license you choose for the
+purposes of making your module available to the Perl 6 community—regardless of what license you choose for the
 rest of your distribution. You also agree not to hold these entities liable for any damage or inconvenience caused
 by the operation of the ecosystem or the failure to do so.