Polish "Fix grammar in README.adoc"

See gh-28835

Author: snicoll

README.adoc

@@ -99,7 +99,7 @@ There are several modules in Spring Boot. Here is a quick overview:
 
 
 === spring-boot
-The main library provides features that support the other parts of Spring Boot. These include:
+The main library providing features that support the other parts of Spring Boot. These include:
 
 * The `SpringApplication` class, providing static convenience methods that can be used to write a stand-alone Spring Application.
   Its sole job is to create and refresh an appropriate Spring `ApplicationContext`.
@@ -114,7 +114,7 @@ Spring Boot can configure large parts of typical applications based on the conte
 A single `@EnableAutoConfiguration` annotation triggers auto-configuration of the Spring context.
 
 Auto-configuration attempts to deduce which beans a user might need. For example, if `HSQLDB` is on the classpath, and the user has not configured any database connections, then they probably want an in-memory database to be defined.
-Auto-configuration will always back away as the user starts to define their beans.
+Auto-configuration will always back away as the user starts to define their own beans.
 
 
 
@@ -143,7 +143,7 @@ This module provides many endpoints, including the `HealthEndpoint`, `Environmen
 This provides auto-configuration for actuator endpoints based on the content of the classpath and a set of properties.
 For instance, if Micrometer is on the classpath, it will auto-configure the `MetricsEndpoint`.
 It contains configuration to expose endpoints over HTTP or JMX.
-Just like Spring Boot AutoConfigure, this will back away as the user starts to define their beans.
+Just like Spring Boot AutoConfigure, this will back away as the user starts to define their own beans.