Improve Pollen sensor templates

[brianjking]

# Pollen
  - platform: rest
    name: pollen_percentage
    resource: https://www.pollen.com/api/forecast/current/pollen/##### <--- ZIP CODE
    value_template: "{{value_json.Location.periods[1].Index}}"
    scan_interval: 21600
    headers:
       Referer: "https://www.pollen.com"
  - platform: template
    sensors:
      pollen_level:
        friendly_name: 'Pollen Level'
        value_template: >
          {% if states.sensor.pollen_percentage.state|float <= 2.4 %}Low
          {% elif states.sensor.pollen_percentage.state|float <= 4.8 %}Low to Medium
          {% elif states.sensor.pollen_percentage.state|float <= 7.2 %}Medium
          {% elif states.sensor.pollen_percentage.state|float <= 9.6 %}Medium to High
          {% elif states.sensor.pollen_percentage.state|float <= 12.0 %}High
          {% else %}Unknown
          {% endif %}

# Flu Sensor
  - platform: rest
    name: cold_flu_percentage
    resource: https://www.pollen.com/api/forecast/extended/cold/##### <--- ZIP CODE
    value_template: "{{value_json.Location.periods[1].Index}}"
    scan_interval: 21600
    headers:
       Referer: "https://www.pollen.com"
  - platform: template
    sensors:
      cold_flu_risk:
        friendly_name: 'Cold & Flu Risk'
        value_template: >
          {% if states.sensor.cold_flu_percentage.state|float <= 2.4 %}Low
          {% elif states.sensor.cold_flu_percentage.state|float <= 4.8 %}Low to Medium
          {% elif states.sensor.cold_flu_percentage.state|float <= 7.2 %}Medium
          {% elif states.sensor.cold_flu_percentage.state|float <= 9.6 %}Medium to High
          {% elif states.sensor.cold_flu_percentage.state|float <= 12.0 %}High
          {% else %}Unknown
          {% endif %}

source: https://community.home-assistant.io/t/pollen-allergy-sensor/10033/6