Update docs/introduction.md

Co-authored-by: Hokeun Kim <[email protected]>

Author: edwardalee

docs/introduction.md

@@ -34,7 +34,7 @@ The reactor-oriented programming paradigm is informally described via the follow
 5. _Flow of Time_ — Successive invocations of any single reaction occur at strictly increasing tags. Any messages that are not read by a reaction triggered at the tag of the message are lost.
 6. _Mutual Exclusion_ — The execution of any two reactions _of the same reactor_ are mutually exclusive (atomic with respect to one another). Moreover, any two reactions that are invoked at the same tag are invoked in the order specified by the reactor definition. This avoids race conditions between reactions accessing the reactor state variables.
 7. _Determinism_ — A Lingua Franca program is deterministic unless the programmer explicit uses nondeterministic constructs. Given the same input data, a composition of reactors has exactly one correct behavior. This makes Lingua Franca programs _testable_.
-8. _Concurrency_ — Dependencies between reactions are explicitly declared in a Lingua Franca program, and reactions that are not dependent on one another can be executed in parallel on a multi-core machine or on parallel. For targets supporting federated execution (currently C, Python, and TypeScript), execution can be distributed across networks.
+8. _Concurrency_ — Dependencies between reactions are explicitly declared in a Lingua Franca program, and reactions that are not dependent on one another can be executed in parallel on a multi-core machine. For targets supporting federated execution (currently C, Python, and TypeScript), execution can be distributed across networks.
 9. _Feedback_ - Messages can flow in feedback cycles. The compiler automatically identifies causality loops that may be introduced by the programmer. A causality loop makes it impossible for the compiler to determine an order of reaction invocation at a tag that preserves determinism.
 
 ## Getting Started