Clarify some details

exercises/13-advanced-jenkinsfile/solution/solution.md

@@ -1,16 +1,9 @@
 # Solution
 
-Create the credentials for the CodeCov token.
-
-![CodeCov Credentials](./images/codecov_token_credentials.png)
-
 You can implement the "Test" stage as follows.
 
 ```groovy
 stage('Test') {
-    environment {
-        CODECOV_TOKEN = credentials('CODECOV_TOKEN')
-    }
     steps {
         sh 'go test ./... -coverprofile=coverage.txt'
         sh "curl -s https://codecov.io/bash | bash -s -"
@@ -23,7 +16,7 @@ You can implement the "Code Analysis" stage as follows.
 ```groovy
 stage('Code Analysis') {
     steps {
-        sh 'curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | bash -s -- -b $GOPATH/bin v1.17.1'
+        sh 'curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | bash -s -- -b $GOPATH/bin v1.18.0'
         sh 'golangci-lint run'
     }
 }
@@ -47,4 +40,48 @@ stage('Release') {
         sh 'curl -sL https://git.io/goreleaser | bash'
     }
 }
+```
+
+The final `Jenkinsfile` looks similar to the solution below.
+
+```groovy
+pipeline {
+    agent any
+    tools {
+        go 'go-1.12'
+    }
+    environment {
+        GO111MODULE = 'on'
+    }
+    stages {
+        stage('Build') {
+            steps {
+                sh 'go build'
+            }
+        }
+        stage('Test') {
+            steps {
+                sh 'go test ./... -coverprofile=coverage.txt'
+                sh "curl -s https://codecov.io/bash | bash -s -"
+            }
+        }
+        stage('Code Analysis') {
+            steps {
+                sh 'curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | bash -s -- -b $GOPATH/bin v1.18.0'
+                sh 'golangci-lint run'
+            }
+        }
+        stage('Release') {
+            when {
+                buildingTag()
+            }
+            environment {
+                GITHUB_TOKEN = credentials('GITHUB_TOKEN')
+            }
+            steps {
+                sh 'curl -sL https://git.io/goreleaser | bash'
+            }
+        }
+    }
+}
 ```