env: fix Makefile typos

Change-Id: I0629392c698204dad4e466c86d392d05bc613868
Reviewed-on: https://go-review.googlesource.com/40851
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

env/crosscompile/linux-armel-stretch/Makefile

@@ -18,7 +18,7 @@ prod: Dockerfile
 	gcloud docker -- push $(PROD_REPO)/$(IMAGE_NAME):latest
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	docker build -t $(REPO)/$(IMAGE_NAME):latest .

env/crosscompile/linux-armhf-jessie/Makefile

@@ -18,7 +18,7 @@ prod: Dockerfile
 	gcloud docker -- push $(PROD_REPO)/$(IMAGE_NAME):latest
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	docker build -t $(REPO)/$(IMAGE_NAME):latest .

env/crosscompile/linux-s390x-stretch/Makefile

@@ -18,7 +18,7 @@ prod: Dockerfile
 	gcloud docker -- push $(PROD_REPO)/$(IMAGE_NAME):latest
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	docker build -t $(REPO)/$(IMAGE_NAME):latest .

env/linux-x86-alpine/Makefile

@@ -17,7 +17,7 @@ prod: Dockerfile
 	gcloud docker -- push $(PROD_REPO)/$(IMAGE_NAME):latest
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	docker build -t $(REPO)/$(IMAGE_NAME):latest .

env/linux-x86-clang/Makefile

@@ -17,7 +17,7 @@ prod: Dockerfile
 	gcloud docker -- push $(PROD_REPO)/$(IMAGE_NAME):latest
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	docker build -t $(REPO)/$(IMAGE_NAME):latest .

env/linux-x86-nacl/Makefile

@@ -21,7 +21,7 @@ prod: Dockerfile
 	rm Dockerfile.make
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	sed 's|{{REPO}}|'"$(REPO)"'|g' Dockerfile > Dockerfile.make

env/linux-x86-std-kube/Makefile

@@ -17,7 +17,7 @@ prod: Dockerfile
 	gcloud docker -- push $(PROD_REPO)/$(IMAGE_NAME):latest
 
 # You must provide a REPO=your-repo-name arg when you make
-# this targarget. REPO is the name of the Docker repository
+# this target. REPO is the name of the Docker repository
 # that will be prefixed to the name of the image being built.
 dev: Dockerfile
 	docker build -t $(REPO)/$(IMAGE_NAME):latest .