correct spelling in context.md
# Context
-The main goal of `Context` is to acquire global data attached to Schema. **Note that if the return value of resolver function is borrowed from `Context`, you need to explictly state the lifetime of the argument.**
+The main goal of `Context` is to acquire global data attached to Schema. **Note that if the return value of resolver function is borrowed from `Context`, you need to explicitly state the lifetime of the argument.**
The following example shows how to borrow data in `Context`.
