Updates the error output for an empty directory

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**What type of PR is this:**

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**What does this PR do / why we need it:**

Updates the error output for running `odo dev` or `odo deploy` in an
empty directory. Telling the user to run the same command in a non-empty
dir, OR use `odo init`.

**Which issue(s) this PR fixes:**
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N/A

**PR acceptance criteria:**

- [X] Unit test

- [X] Integration test

- [X] Documentation

**How to test changes / Special notes to the reviewer:**

Signed-off-by: Charlie Drage <[email protected]>

pkg/odo/cli/deploy/deploy.go

@@ -65,7 +65,7 @@ func (o *DeployOptions) Complete(cmdline cmdline.Cmdline, args []string) (err er
 		return err
 	}
 	if isEmptyDir {
-		return errors.New("this command cannot run in an empty directory, you need to run it in a directory containing source code")
+		return errors.New("This command cannot run in an empty directory. Run the command in a directory containing source code.\nIf you wish to initialize a new project with sample source code, use 'odo init'.")
 	}
 
 	initFlags := o.clientset.InitClient.GetFlags(cmdline.GetFlags())

pkg/odo/cli/dev/dev.go

@@ -89,7 +89,7 @@ func (o *DevOptions) Complete(cmdline cmdline.Cmdline, args []string) error {
 		return err
 	}
 	if isEmptyDir {
-		return errors.New("this command cannot run in an empty directory, you need to run it in a directory containing source code")
+		return errors.New("This command cannot run in an empty directory. Run the command in a directory containing source code.\nIf you wish to initialize a new project with sample source code, use 'odo init'.")
 	}
 	initFlags := o.clientset.InitClient.GetFlags(cmdline.GetFlags())
 	err = o.clientset.InitClient.InitDevfile(initFlags, o.contextDir,

tests/integration/devfile/cmd_dev_test.go

@@ -45,7 +45,7 @@ var _ = Describe("odo dev command tests", func() {
 
 		It("should error", func() {
 			output := helper.Cmd("odo", "dev").ShouldFail().Err()
-			Expect(output).To(ContainSubstring("this command cannot run in an empty directory"))
+			Expect(output).To(ContainSubstring("This command cannot run in an empty directory"))
 
 		})
 	})

tests/integration/devfile/cmd_devfile_deploy_test.go

@@ -35,7 +35,7 @@ var _ = Describe("odo devfile deploy command tests", func() {
 
 		It("should error", func() {
 			output := helper.Cmd("odo", "deploy").ShouldFail().Err()
-			Expect(output).To(ContainSubstring("this command cannot run in an empty directory"))
+			Expect(output).To(ContainSubstring("This command cannot run in an empty directory"))
 
 		})
 	})