Merge pull request #5 from lolli42/lolli-1

[TASK] More info on Readme.md

Author: ervaude

Readme.md

@@ -1,10 +1,31 @@
 # EXT: host_variants
 
-This extension allows to configure a base variant in TYPO3s Site Configuration depending on the current Host.
+This extension allows to configure a base variant in TYPO3s Site Configuration depending
+on the current Host.
+
+## When is it useful?
+
+This extension can be useful when dealing with multiple sites in one TYPO3 instance
+with different domains:
+
+Let's say you have a primary domain `primary-domain.tld` with a site configuration.
+Backend editors log in to this primary domain.
+
+You have a site config with an own page tree for a second domain `another-domain.tld`.
+Editors create content for the second domain on a hidden page. When previewing that
+page from within the backend, `another-domain.tld/some-page-slug` will be shown. Since
+editors are logged in to the primary domain, the backend user cookie will not be sent by
+the browser for the secondary domain, the frontend does not see a logged in backend
+user and will show a 404.
+
+The extension now allows configuring a site base variant for the secondary domain that
+kicks in when backend preview is called from the main domain, and calls the frontend
+of the secondary site as a sub path of the main domain instead.
+
 
 ## Requirements
 
-* TYPO3 9 LTS, 10 LTS or 11.0
+* TYPO3 9 LTS, 10 LTS, 11 LTS, 12 LTS
 
 ## Installation and Setup
 Install the extension via your preferred way. No further setup is required.
@@ -16,20 +37,30 @@ This allows configuring multiple domains for the same root page.
 
 ## Example
 
+Basic:
+
 ```yaml
-base: 'https://main-domain.tld/'
+base: 'https://another-domain.tld/'
 baseVariants:
   -
-    base: 'https://another-domain.tld/'
-    condition: 'host == "another-domain.tld"'
+    base: 'https://primary-domain.tld/some-sub-path'
+    condition: 'host == "primary-domain.tld"'
+```
+
+Using some ENV variable:
+
+```yaml
+base: 'https://another-domain.tld/'
+baseVariants:
   -
-    base: 'http://%env(DYNAMIC_DOMAIN)%/'
-    condition: 'host == "%env(DYNAMIC_DOMAIN)%"'
+    base: 'https://%env(MAIN_DOMAIN)%/some-sub-path'
+    condition: 'host == "%env(MAIN_DOMAIN)%"'
 ```
 
-Conditions can also be combined:
+Combining conditions:
+
 ```yaml
-base: 'https://main-domain.tld/'
+base: 'https://another-domain.tld/'
 baseVariants:
   -
     base: 'https://local1.local/'