Proofread README.md (#67)

Minor proofreading

README.md

@@ -123,8 +123,8 @@ from executing the tasks.
 - If the route is defined `async` then it's called regularly via `await` 
 and FastAPI trusts you to do only non-blocking I/O operations.
 
-The caveat is if you fail that trust and execute blocking operations within async routes, 
-the event loop will not be able to run the next tasks until that blocking operation is done.
+The caveat is that if you violate that trust and execute blocking operations within async routes,
+the event loop will not be able to run subsequent tasks until the blocking operation completes.
 ```python
 import asyncio
 import time
@@ -346,7 +346,7 @@ If we didn't put data validation to dependency, we would have to validate `post_
 for every endpoint and write the same tests for each of them. 
 
 ### Chain Dependencies
-Dependencies can use other dependencies and avoid code repetition for the similar logic.
+Dependencies can use other dependencies and avoid code repetition for similar logic.
 ```python
 # dependencies.py
 from fastapi.security import OAuth2PasswordBearer
@@ -474,7 +474,7 @@ Developing RESTful API makes it easier to reuse dependencies in routes like thes
    2. `GET /courses/:course_id/chapters/:chapter_id/lessons`
    3. `GET /chapters/:chapter_id`
 
-The only caveat is to use the same variable names in the path:
+The only caveat is having to use the same variable names in the path:
 - If you have two endpoints `GET /profiles/:profile_id` and `GET /creators/:creator_id`
 that both validate whether the given `profile_id` exists,  but `GET /creators/:creator_id`
 also checks if the profile is creator, then it's better to rename `creator_id` path variable to `profile_id` and chain those two dependencies.
@@ -510,11 +510,16 @@ async def get_user_profile_by_id(
 
 ```
 ### FastAPI response serialization
-If you think you can return Pydantic object that matches your route's `response_model` to make some optimizations,
-then it's wrong. 
+You may think you can return Pydantic object that matches your route's `response_model` to make some optimizations,
+but you'd be wrong.
 
-FastAPI firstly converts that pydantic object to dict with its `jsonable_encoder`, then validates 
+FastAPI first converts that pydantic object to dict with its `jsonable_encoder`, then validates 
 data with your `response_model`, and only then serializes your object to JSON.
+
+This means your Pydantic model object is created twice:
+- First, when you explicitly create it to return from your route.
+- Second, implicitly by FastAPI to validate the response data according to the response_model.
+
 ```python
 from fastapi import FastAPI
 from pydantic import BaseModel, root_validator