Merge pull request #1251 from shaarli/doc-update-php-compat

doc: update PHP compatibility table

doc/md/Server-configuration.md

@@ -18,7 +18,7 @@ Version | Status | Shaarli compatibility
 7.2 | Supported | Yes
 7.1 | Supported | Yes
 7.0 | Supported | Yes
-5.6 | Supported | Yes
+5.6 | EOL: 2018-12-31 | Yes (up to Shaarli 0.10.x)
 5.5 | EOL: 2016-07-10 | Yes
 5.4 | EOL: 2015-09-14 | Yes (up to Shaarli 0.8.x)
 5.3 | EOL: 2014-08-14 | Yes (up to Shaarli 0.8.x)