docs: sentence-case sweep across 4 more pages

- platforms/digitalocean: Cost Comparison (2026), Oracle Cloud Free Alternative
- gateway/remote-gateway-readme: Quick Setup, How It Works
- cli/crestodian: Setup Bootstrap
- plugins/codex-harness: Computer Use
(Brand-named headings preserved across azure.md, web.md, firecrawl.md, clawhub.md, config-channels.md, security/index.md.)

docs/platforms/digitalocean.md

@@ -14,7 +14,7 @@ Run a persistent OpenClaw Gateway on DigitalOcean for **$6/month** (or $4/mo wit
 
 If you want a $0/month option and don’t mind ARM + provider-specific setup, see the [Oracle Cloud guide](/platforms/oracle).
 
-## Cost Comparison (2026)
+## Cost comparison (2026)
 
 | Provider     | Plan            | Specs                  | Price/mo    | Notes                                 |
 | ------------ | --------------- | ---------------------- | ----------- | ------------------------------------- |
@@ -209,7 +209,7 @@ openclaw backup create
 
 ---
 
-## Oracle Cloud Free Alternative
+## Oracle Cloud free alternative
 
 Oracle Cloud offers **Always Free** ARM instances that are significantly more powerful than any paid option here — for $0/month.