[doc] Jumbo builds can't be considered experimental anymore

Change-Id: I88b641bf356044ca94552273081af22c0fde1795
Reviewed-on: https://chromium-review.googlesource.com/c/1341530
Reviewed-by: Fredrik Söderquist <fs@opera.com>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#609218}

docs/windows_build_instructions.md

@@ -222,7 +222,7 @@ in the editor that appears when you create your output directory
 (`gn args out/Default`) or on the gn gen command line
 (`gn gen out/Default --args="is_component_build = true is_debug = true"`).
 Some helpful settings to consider using include:
-* `use_jumbo_build = true` - *experimental* [Jumbo/unity](jumbo.md) builds.
+* `use_jumbo_build = true` - [Jumbo/unity](jumbo.md) builds.
 * `is_component_build = true` - this uses more, smaller DLLs, and incremental
 linking.
 * `enable_nacl = false` - this disables Native Client which is usually not