fixes typos

component/packer/debian77.json.jinja2

@@ -2,7 +2,7 @@
     "variables": {
         "user": "nexedi",
         "password": "test",
-        "disk_size": ${disk-size},
+        "disk_size": ${disk_size},
         "domain": ""
     },
 

component/packer/instance.cfg.in

@@ -33,7 +33,7 @@ partition = $${slap_connection:partition_id}
 url = $${slap_connection:server_url}
 key = $${slap_connection:key_file}
 cert = $${slap_connection:cert_file}
-configuration.packer_json = ${:_profile_base_location_}/debian77.json.cfg
+configuration.packer_json = ${:_profile_base_location_}/debian77.json.jinja2
 
 [packer-json-template]
 recipe = slapos.recipe.template