[LOS-1030] Add almalinux documentation - locmap

• Add locmap and installation documentation related to alma8 and alma9
• Remove links that doesn't exist anymore: https://linux.web.cern.ch/centos8/docs/migration - /centos8/docs/migration

docs/almalinux/alma8/index.md

+# AlmaLinux 8 Documentation
+  
+* [Documentation pages](/almalinux/alma8)
+    * [Installation instructions](/almalinux/alma8/install)
+    * [Locmap installation](/almalinux/alma8/locmap)
+
+Please check <a href="../../docs/">Documentation</a> for additional documentation.
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