Update Chrome OS to ChromeOS in enterprise documentation

Chrome OS to ChromeOS renaming already happened in policy_templates.json
(http://crrev/c/3578274). But enterprise docs still refer to Chrome OS
which is particularly unfortunate in case of description_guidelines.md
which dictates how to write policy descriptions in
policy_templates.json. This cl updates the names to ChromeOS in all docs
under /docs/enterprise/.

Bug: 1302482
Change-Id: Ide022d47e08aa80434fb601ecb60195c826620ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3757860
Commit-Queue: Andrey Davydov <[email protected]>
Reviewed-by: Roman Sorokin <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1024637}
diff --git a/docs/enterprise/enrollment.md b/docs/enterprise/enrollment.md
index d875342..8e879be 100644
--- a/docs/enterprise/enrollment.md
+++ b/docs/enterprise/enrollment.md
@@ -1,4 +1,4 @@
-# Enterprise Enrollment on Chrome OS
+# Enterprise Enrollment on ChromeOS
 
 Enterprise Enrollment is a process that marks a device as belonging to
 particular organization and enables [management](management.md) of the device