Update Gradle/Wrapper to latest version (#497)

* Update Gradle/Wrapper to latest version

* Update gradle wrapper to version 6.8.3

* add ASF license header to generated gradle-wrapper.properties file

* Update README to reflect current gradlew version supported

* Update README to reflect current gradlew version supported

* Update README to reflect current gradlew version supported

Author: mrutkows

README.md

@@ -192,7 +192,7 @@ The project includes its own packaged version of Gradle called Gradle Wrapper wh
 
 #### Using your own local Gradle to build
 
-Alternatively, you can choose to [Install Gradle](https://gradle.org/install/) and use it instead of the project's Gradle Wrapper.  If so, you would use the `gradle` command instead of `gradlew`. If you do elect to use your own Gradle, verify its version is `6.6` or higher:
+Alternatively, you can choose to [Install Gradle](https://gradle.org/install/) and use it instead of the project's Gradle Wrapper.  If so, you would use the `gradle` command instead of `gradlew`. If you do elect to use your own Gradle, verify its version is `6.8.1` or higher:
 
 ```sh
 gradle -version
@@ -209,6 +209,8 @@ $ go get -u github.com/jteeuwen/go-bindata/...
 $ go-bindata -pkg wski18n -o wski18n/i18n_resources.go wski18n/resources
 ```
 
+> **Note**: the `go-bindata` package will automatically be installed if the `go build` command is used in the project as it is listed in the `go.mod` dependency file.
+
 ### Running unit tests
 
 ##### Using Go
@@ -296,7 +298,7 @@ go get github.com/project/libname
 Using a release tag:
 
 ```sah
-go get github.com/project/libname
+go get github.com/project/libname@1.1.0
 ```
 
 Using a commit hash:

gradle/wrapper/gradle-wrapper.jar

@@ -16,6 +16,6 @@
 #
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-all.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https://services.gradle.org/distributions/gradle-6.6-all.zip