How to use global variable in symfony twig file?

I have done setting in app/config/config.yml

twig:

globals:

  mandatory_note: %mandatory_note%

parameter also set in config.yml file

parameters:

mandatory_note: "Note: * marked fields are mandatory"

And in twig file I have accessed the variable

{{ mandatory_note }}

but still gets error. ie. mandatory_note variable doesnot exists.

This is my config.yml file

imports:
    - { resource: parameters.yml }
    - { resource: security.yml }
    - { resource: services.yml }

framework:
    #esi:             ~
    translator:      { fallbacks: ["%locale%"] }
    secret:          "%secret%"
    router:
        resource: "%kernel.root_dir%/config/routing.yml"
        strict_requirements: ~
    form:            ~
    csrf_protection: ~
    validation:      { enable_annotations: true }
    templating:
        engines: ['twig']
        #assets_version: SomeVersionScheme
    default_locale:  "%locale%"
    trusted_hosts:   ~
    trusted_proxies: ~
    session:
        cookie_lifetime: 0
        gc_maxlifetime: 36000
        # handler_id set to null will use default session handler from php.ini
        handler_id:  ~
    fragments:       ~
    http_method_override: true

# Twig Configuration
twig:
    debug:            "%kernel.debug%"
    strict_variables: "%kernel.debug%"

# Assetic Configuration
assetic:
    debug:          "%kernel.debug%"
    use_controller: false
    bundles:        []
    #java: /usr/bin/java
    filters:
        cssrewrite: ~
        #closure:
        #    jar: "%kernel.root_dir%/Resources/java/compiler.jar"
        #yui_css:
        #    jar: "%kernel.root_dir%/Resources/java/yuicompressor-2.4.7.jar"

# Doctrine Configuration
doctrine:
    dbal:
        driver:   "%database_driver%"
        host:     "%database_host%"
        port:     "%database_port%"
        dbname:   "%database_name%"
        user:     "%database_user%"
        password: "%database_password%"
        unix_socket: "/opt/lampp/var/mysql/mysql.sock"
        charset:  UTF8
        mapping_types: 
            enum:       integer
        # if using pdo_sqlite as your database driver:
        #   1. add the path in parameters.yml
        #     e.g. database_path: "%kernel.root_dir%/data/data.db3"
        #   2. Uncomment database_path in parameters.yml.dist
        #   3. Uncomment next line:
        #     path:     "%database_path%"

    orm:
        auto_generate_proxy_classes: "%kernel.debug%"
        auto_mapping: true

# Swiftmailer Configuration
swiftmailer:
    transport: "%mailer_transport%"
    host:      "%mailer_host%"
    username:  "%mailer_user%"
    password:  "%mailer_password%"
    spool:     { type: memory }
    encryption: "%mailer_encryption%"
    port: "%mailer_port%"
    sender_address: "%mailer_sender%"
parameters:
    max_contents_per_page: 20
    max_pages_per_page: 10
    mandatory_note: "Note: * marked fields are mandatory"

twig:
    globals:
        mandatory_note: %mandatory_note%