Merge pull request #246 from Be-ing/its

intro: remove incorrect '

Author: nrc

src/intro.md

@@ -21,7 +21,7 @@ In concurrent programming, the program does multiple things at the same time (or
 
 Because the operating system is not involved, *context switching* in the async world is very fast. Furthermore, async tasks have much lower memory overhead than operating system threads. This makes async programming a good fit for systems which need to handle very many concurrent tasks and where those tasks spend a lot of time waiting (for example, for client responses or for IO). It also makes async programming a good fit for microcontrollers with very limited amounts of memory and no operating system that provides threads.
 
-Async programming also offers the programmer fine-grained control over how tasks are executed (levels of parallelism and concurrency, control flow, scheduling, and so forth). This means that async programming can be expressive as well as ergonomic for many uses. In particular, async programming in Rust has a powerful concept of cancellation and supports many different flavours of concurrency (expressed using constructs including `spawn` and it's variations, `join`, `select`, `for_each_concurrent`, etc.). These allow composable and reusable implementations of concepts like timeouts, pausing, and throttling.
+Async programming also offers the programmer fine-grained control over how tasks are executed (levels of parallelism and concurrency, control flow, scheduling, and so forth). This means that async programming can be expressive as well as ergonomic for many uses. In particular, async programming in Rust has a powerful concept of cancellation and supports many different flavours of concurrency (expressed using constructs including `spawn` and its variations, `join`, `select`, `for_each_concurrent`, etc.). These allow composable and reusable implementations of concepts like timeouts, pausing, and throttling.
 
 
 ## Hello, world!