GH-3461: Readme Polishing, eclipse and build

Resolves https://github.com/spring-projects/spring-integration/issues/3461

* Fix project URL
* Fix IDEA instructions

README.md

@@ -16,7 +16,17 @@ To check out the project and build from the source, do the following:
 
     git clone git://github.com/spring-projects/spring-integration.git
     cd spring-integration
-    ./gradlew build
+    ./gradlew clean test
+
+    or
+
+    ./gradlew clean testAll
+
+The latter runs additional tests (those annotated with `@LongRunningIntegrationTest`); it is a more thorough test but takes quite a lot longer to run.
+
+The test results are captured in `build/reports/tests/test` (or `.../testAll`) under each module (in HTML format).
+
+Add `--continue` to the command to perform a complete build, even if there are failing tests in some modules; otherwise the build will stop after the current module(s) being built are completed.
 
 **NOTE:** While Spring Integration runs with Java SE 8 or higher, a Java 11 compiler is required to build the project.
 
@@ -36,28 +46,36 @@ To build complete distribution including `-dist`, `-docs`, and `-schema` zip fil
 
     ./gradlew dist
 
-# Using Eclipse
+# Using Eclipse or Spring Tool Suite (with BuildShip Plugin)
 
-To generate Eclipse metadata (.classpath and .project files), do the following:
+If you have the BuildShip plugin installed,
+
+*File -> Import -> Gradle -> Existing Gradle Project*
+
+# Using Eclipse or Spring Tool Suite (when the BuildShip Plugin is not installed)
+
+To generate Eclipse metadata (.classpath and .project files, etc), do the following:
 
     ./gradlew eclipse
 
 Once complete, you may then import the projects into Eclipse as usual:
 
- *File -> Import -> Existing projects into workspace*
+ *File -> Import -> General -> Existing projects into workspace*
 
 Browse to the *'spring-integration'* root directory. All projects should import
 free of errors.
 
 # Using IntelliJ IDEA
 
-To generate IDEA metadata (.iml and .ipr files), do the following:
+To import the project into IntelliJ IDEA:
 
-    ./gradlew idea
+File -> Open... -> and select build.gradle from spring-integration project root directory
+
+# Guidelines
 
 See also [Contributor Guidelines](https://github.com/spring-projects/spring-integration/blob/master/CONTRIBUTING.adoc).
 
 # Resources
 
 For more information, please visit the Spring Integration website at:
-[https://projects.spring.io/spring-integration](https://projects.spring.io/spring-integration/)
+[https://spring.io/projects/spring-integration](https://spring.io/projects/spring-integration/)