add url to templates

docs/user_guide/add_template.rst

@@ -19,6 +19,7 @@ This example installs :code:`jq`, a
     # The name of the software. This becomes the name in the template registry.
     # The CLI option would be rendered as `--jq`.
     name: jq
+    url: https://jqlang.github.io/jq/
     # An alert that is printed when using this template in the CLI.
     alert: Please be advised that this software uses
     # How to install this software from pre-compiled binaries.

foo

@@ -0,0 +1,20 @@
+# Generated by Neurodocker and Reproenv.
+
+FROM ubuntu
+
+# Save specification to JSON.
+RUN printf '{ \
+  "pkg_manager": "apt", \
+  "existing_users": [ \
+    "root" \
+  ], \
+  "instructions": [ \
+    { \
+      "name": "from_", \
+      "kwds": { \
+        "base_image": "ubuntu" \
+      } \
+    } \
+  ] \
+}' > /.reproenv.json
+# End saving to specification to JSON.