Update issue.rst (#2307)

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doc/contrib/issue.rst

@@ -5,7 +5,7 @@ File an Issue
 
 If you have found a bug or problem in Arbor, or want to request a feature, you
 can use our `issue tracker <https://github.com/arbor-sim/arbor/issues>`__. If
-you issue is not yet filed in the issue tracker, please do so and describe the
-problem, bug or feature as best you can. You can add supporting data, code or
-documents to help make your point. For bugs in particular, stacktraces (either
+your issue is not yet filed in the issue tracker, please do so and describe the
+problem, bug, or feature as best you can. You can add supporting data, code, or
+documents to help make your point. For bugs in particular, stack traces (either
 from inside a debugger or by enabling ``ARB_BACKTRACE``) are extremely useful.