Minor edits to Vaccines section (#436)

**On Vaccines home**, changed:
Add and edit your vaccines for your organisation.  
To:
Add and edit vaccines for your organisation.

On **Choose a site,** changed:
H1 from 'Site' to 'Choose a site'
Changed para below H1 from:
'Vaccines and batch information are added to sites within your Trust.'
to:
'Select the site where you want to add a vaccine.'

---------

Co-authored-by: Frankie Roberto <[email protected]>
Co-authored-by: Frankie Roberto <[email protected]>

Author: Anna-Sutton

app/views/vaccines/choose-site.html

@@ -1,6 +1,6 @@
 {% extends 'layout.html' %}
 
-{% set pageName = "Site" %}
+{% set pageName = "Choose a site" %}
 
 
 {% set currentSection = "vaccines" %}
@@ -19,9 +19,9 @@
       <div class="nhsuk-grid-row">
         <div class="nhsuk-grid-column-two-thirds">
 
-          <h1 class="nhsuk-heading-xl">Site</h1>
+          <h1 class="nhsuk-heading-xl">Choose a site</h1>
 
-          <p>Vaccines and batch information are added to sites within your Trust.</p>
+          <p>Select the site where you want to add a vaccine.</p>
 
           <p>You can <a href="https://digital.nhs.uk/services/organisation-data-service/request-a-new-code-or-update-organisation-details#site-request" target="_new">request a new site (opens in new tab)</a>.</p>
 

app/views/vaccines/index.html

@@ -17,7 +17,7 @@
 
       <h1 class="nhsuk-heading-xl">Vaccines</h1>
 
-      <p class="nhsuk-body-l">Add and edit your vaccines for your organisation.</p>
+      <p class="nhsuk-body-l">Add and edit vaccines for your organisation.</p>
 
       {{ button({
         "text": "Add vaccine",