Update size on disk figures for Elastic Agent (#1453) (#1469)

* Update size on disk figures for Elastic Agent

* Update install-elastic-agent.asciidoc

(cherry picked from commit ee710a7)

Co-authored-by: Amit Kanfer <[email protected]>

Author: mergify[bot]

docs/en/ingest-management/elastic-agent/install-elastic-agent.asciidoc

@@ -100,11 +100,11 @@ The disk requirements for {agent} vary by operating system and {stack} version.
 
 [options,header]
 |===
-|Operating system |8.13 |8.14
+|Operating system |8.13 | 8.14 | 8.15
 
-| **Linux** | 1800 MB | 1018 MB
-| **macOS** | 1100 MB | 619 MB
-| **Windows** | 891 MB | 504 MB
+| **Linux** | 1800 MB | 1018 MB | 1060 MB
+| **macOS** | 1100 MB | 619 MB | 680 MB
+| **Windows** | 891 MB | 504 MB | 500 MB
 |===
 
 During upgrades, double the disk space is required to store the new {agent} binary. After the upgrade completes, the original {agent} is removed from disk to free up the space.