fix : typo (vuejs#1534)

Author: BirajMainali

src/guide/scaling-up/sfc.md

@@ -74,7 +74,7 @@ In actual projects, we typically integrate the SFC compiler with a build tool su
 
 Some users coming from a traditional web development background may have the concern that SFCs are mixing different concerns in the same place - which HTML/CSS/JS were supposed to separate!
 
-To answer this question, it is important for us to agree that **separation of concerns is not equal to separation of file types.** The ultimate goal of engineering principles is to improve maintainability of codebases. Separation of concerns, when applied dogmatically as separation of file types, does not help us reach that goal in the context of increasingly complex frontend applications.
+To answer this question, it is important for us to agree that **separation of concerns is not equal to the separation of file types.** The ultimate goal of engineering principles is to improve the maintainability of codebases. Separation of concerns, when applied dogmatically as separation of file types, does not help us reach that goal in the context of increasingly complex frontend applications.
 
 In modern UI development, we have found that instead of dividing the codebase into three huge layers that interweave with one another, it makes much more sense to divide them into loosely-coupled components and compose them. Inside a component, its template, logic, and styles are inherently coupled, and collocating them actually makes the component more cohesive and maintainable.