Fixes intelsdi-x#1477, Added information about not recommended charac…

…ters as a namespace separators in the task manifest

docs/TASKS.md

@@ -30,7 +30,12 @@ A task can be in the following states:
 
 ## Task Manifest
 
-A task is described in a task _manifest_, which can be either JSON or YAML<sup>1</sup>. The manifest is divided into two parts: Header and Workflow.
+A task is described in a task _manifest_, which can be either JSON or YAML<sup>1</sup>.
+
+The task manifest must be created as a valid file, be aware of using special characters like  `\` for JSON and `|` for YAML, for details
+see [JSON documentation](http://www.json.org/) and [YAML documentation](http://www.yaml.org/).
+
+The manifest is divided into two parts: Header and Workflow.
 
 ### The Header
 
@@ -207,7 +212,13 @@ More information about the architecture behind this can be found [here](DISTRIBU
 
 #### collect
 
-The collect section describes which metrics are requested to be collected.
+The collect section describes which metrics, indicated by namespaces, are requested to be collected.
+
+Elements of namespace are separated by **namespace separator** which can be defined in the task manifest as different characters,
+with some limitations specific for format of the task manifest.
+It is not recommended to use following characters in the task manifest as the namespace separator:
+- for YAML: `|`,`#`, `$`, `>`,`*`, `,`,`[`, `]`,`{`,`}`,`!`,`"`, ` \``,`%`,`@`
+- for JSON: `\`, `$`,`"`, `*`
 
 Metrics can be enumerated using: