Add helper to telephone number field in hand raise modal

ee/app/assets/javascripts/hand_raise_leads/hand_raise_lead/components/hand_raise_lead_button.vue

@@ -268,6 +268,7 @@ export default {
       <gl-form-group
         :label="$options.i18n.phoneNumberLabel"
         label-size="sm"
+        :description="$options.i18n.phoneNumberDescription"
         label-for="phoneNumber"
       >
         <gl-form-input

ee/app/assets/javascripts/hand_raise_leads/hand_raise_lead/constants.js

@@ -7,6 +7,7 @@ export const i18n = Object.freeze({
   companySizeLabel: __('Number of employees'),
   companySizeSelectPrompt: __('- Select -'),
   phoneNumberLabel: __('Telephone number'),
+  phoneNumberDescription: __('Provide a number our sales team can use to call you.'),
   countryLabel: __('Country'),
   countrySelectPrompt: __('Please select a country'),
   stateLabel: __('State/Province/City'),

locale/gitlab.pot

@@ -27791,6 +27791,9 @@ msgstr ""
 msgid "Protip: %{linkStart}Auto DevOps%{linkEnd} uses Kubernetes clusters to deploy your code!"
 msgstr ""
 
+msgid "Provide a number our sales team can use to call you."
+msgstr ""
+
 msgid "Provider"
 msgstr ""