Add missing .

node/README.md

@@ -48,7 +48,7 @@ software such as Apache.
 
 You can then build and run the Docker image:
 
-    docker build -t my-nodejs-app
+    docker build -t my-nodejs-app .
     docker run -it --rm --name my-running-app my-nodejs-app
 
 ### Notes

node/content.md

@@ -30,7 +30,7 @@ software such as Apache.
 
 You can then build and run the Docker image:
 
-    docker build -t my-nodejs-app
+    docker build -t my-nodejs-app .
     docker run -it --rm --name my-running-app my-nodejs-app
 
 ### Notes

perl/README.md

@@ -32,7 +32,7 @@ including C, shell scripting (sh), AWK, and sed.
 
 Then, build and run the Docker image:
 
-    docker build -t my-perl-app
+    docker build -t my-perl-app .
     docker run -it --rm --name my-running-app my-perl-app
 
 ## Run a single Perl script

perl/content.md

@@ -19,7 +19,7 @@ including C, shell scripting (sh), AWK, and sed.
 
 Then, build and run the Docker image:
 
-    docker build -t my-perl-app
+    docker build -t my-perl-app .
     docker run -it --rm --name my-running-app my-perl-app
 
 ## Run a single Perl script

python/README.md

@@ -47,7 +47,7 @@ to bootstrap most applications. The build will `COPY` a `requirements.txt` file,
 
 You can then build and run the Docker image:
 
-    docker build -t my-python-app
+    docker build -t my-python-app .
     docker run -it --rm --name my-running-app my-python-app
 
 ## Run a single Python script

python/content.md

@@ -32,7 +32,7 @@ to bootstrap most applications. The build will `COPY` a `requirements.txt` file,
 
 You can then build and run the Docker image:
 
-    docker build -t my-python-app
+    docker build -t my-python-app .
     docker run -it --rm --name my-running-app my-python-app
 
 ## Run a single Python script