add compatibility matrix to docs

.github/workflows/docs.yml

@@ -4,6 +4,9 @@ on:
   push:
     tags:
       - '*'
+    branches:
+      - main
+      - docs
 
 jobs:
 

docs/010_Installation.md

@@ -12,6 +12,22 @@ The 2.x releases require PHP >= 7.0 but don't get feature updates any longer. Bu
 
 The 1.x release line has support for PHP >= 5.4. Bugfixes won't be backported.
 
+### Compatibility Matrix
+
+| PHP Version | phpgeo Version | Support Status   | Composer Install                         |
+|:-----------:|:--------------:|:----------------:|------------------------------------------|
+| 8.2         | 4.x            | ✅ active         | `composer require mjaschen/phpgeo`      |
+| 8.1         | 4.x            | ✅ active         | `composer require mjaschen/phpgeo`      |
+| 8.0         | 4.x            | ✅ active         | `composer require mjaschen/phpgeo`      |
+| 7.4         | 4.x            | ✅ active         | `composer require mjaschen/phpgeo`      |
+| 7.3         | 4.x            | ✅ active         | `composer require mjaschen/phpgeo`      |
+| 7.2         | 3.x            | ⚠️ security only   | `composer require mjaschen/phpgeo:^3.0` |
+| 7.1         | 2.x            | ❌ end of life     | `composer require mjaschen/phpgeo:^2.0` |
+| 7.0         | 2.x            | ❌ end of life     | `composer require mjaschen/phpgeo:^2.0` |
+| 5.6         | 1.x            | ❌ end of life     | `composer require mjaschen/phpgeo:^1.0` |
+| 5.5         | 1.x            | ❌ end of life     | `composer require mjaschen/phpgeo:^1.0` |
+| 5.4         | 1.x            | ❌ end of life     | `composer require mjaschen/phpgeo:^1.0` |
+
 ## Installation
 
 *phpgeo* is best be installed using Composer. Please visit the