docs: Related CardGroups + typography hygiene across 4 pages

docs/install/clawdock.md: renamed '## Related pages' to '## Related'
for consistency with sibling install docs and converted the 3-bullet
list into a CardGroup linking docker, docker-vm-runtime, and updating.

docs/install/nix.md: replaced 2 typography characters with ASCII
equivalents and converted the 3-bullet Related list into a CardGroup,
adding an Updating card so readers wiring nix-openclaw next to a
managed install see the upgrade path.

docs/concepts/features.md: converted the 2-bullet Related list into a
CardGroup, adding cross-links to channels and plugins so the page now
points readers at both deeper concepts (experimental features, agent
runtime) and direct surfaces (channels, plugins).

docs/tools/pdf.md: replaced 2 typography characters with ASCII
equivalents.

docs/concepts/features.md

@@ -75,5 +75,17 @@ title: "Features"
 
 ## Related
 
-- [Experimental features](/concepts/experimental-features)
-- [Agent runtime](/concepts/agent)
+<CardGroup cols={2}>
+  <Card title="Experimental features" href="/concepts/experimental-features" icon="flask">
+    Opt-in features that have not yet shipped to the default surface.
+  </Card>
+  <Card title="Agent runtime" href="/concepts/agent" icon="robot">
+    Agent runtime model and how runs are dispatched.
+  </Card>
+  <Card title="Channels" href="/channels" icon="message-square">
+    Connect Telegram, WhatsApp, Discord, Slack, and more from one Gateway.
+  </Card>
+  <Card title="Plugins" href="/tools/plugin" icon="plug">
+    Bundled and third-party plugins that extend OpenClaw.
+  </Card>
+</CardGroup>

docs/install/clawdock.md

@@ -97,8 +97,16 @@ ClawDock works with the same Docker config split described in [Docker](/install/
 
 Use `clawdock-show-config` when you want to inspect the `.env` files and `openclaw.json` quickly. It redacts `.env` values in its printed output.
 
-## Related pages
+## Related
 
-- [Docker](/install/docker)
-- [Docker VM Runtime](/install/docker-vm-runtime)
-- [Updating](/install/updating)
+<CardGroup cols={2}>
+  <Card title="Docker" href="/install/docker" icon="docker">
+    Canonical Docker install for OpenClaw.
+  </Card>
+  <Card title="Docker VM runtime" href="/install/docker-vm-runtime" icon="cube">
+    Docker-managed VM runtime for hardened isolation.
+  </Card>
+  <Card title="Updating" href="/install/updating" icon="arrow-up-right-from-square">
+    Updating the OpenClaw package and managed services.
+  </Card>
+</CardGroup>

docs/install/nix.md

@@ -7,7 +7,7 @@ read_when:
 title: "Nix"
 ---
 
-Install OpenClaw declaratively with **[nix-openclaw](https://github.com/openclaw/nix-openclaw)** — a batteries-included Home Manager module.
+Install OpenClaw declaratively with **[nix-openclaw](https://github.com/openclaw/nix-openclaw)** - a batteries-included Home Manager module.
 
 <Info>
 The [nix-openclaw](https://github.com/openclaw/nix-openclaw) repo is the source of truth for Nix installation. This page is a quick overview.
@@ -87,13 +87,24 @@ plugins and tools that shell out to `nix`-installed executables work without
 manual PATH setup:
 
 - When `NIX_PROFILES` is set, every entry is added to the service PATH in
-  right-to-left precedence (matches Nix shell precedence — rightmost wins).
+  right-to-left precedence (matches Nix shell precedence - rightmost wins).
 - When `NIX_PROFILES` is unset, `~/.nix-profile/bin` is added as a fallback.
 
 This applies to both macOS launchd and Linux systemd service environments.
 
 ## Related
 
-- [nix-openclaw](https://github.com/openclaw/nix-openclaw) -- full setup guide
-- [Wizard](/start/wizard) -- non-Nix CLI setup
-- [Docker](/install/docker) -- containerized setup
+<CardGroup cols={2}>
+  <Card title="nix-openclaw" href="https://github.com/openclaw/nix-openclaw" icon="arrow-up-right-from-square">
+    Source-of-truth Home Manager module and full setup guide.
+  </Card>
+  <Card title="Setup wizard" href="/start/wizard" icon="wand-magic-sparkles">
+    Non-Nix CLI setup walkthrough.
+  </Card>
+  <Card title="Docker" href="/install/docker" icon="docker">
+    Containerized setup as a non-Nix alternative.
+  </Card>
+  <Card title="Updating" href="/install/updating" icon="arrow-up-right-from-square">
+    Updating Home Manager-managed installs alongside the package.
+  </Card>
+</CardGroup>

docs/tools/pdf.md

@@ -191,5 +191,5 @@ Page-filtered fallback model:
 
 ## Related
 
-- [Tools Overview](/tools) — all available agent tools
-- [Configuration Reference](/gateway/config-agents#agent-defaults) — pdfMaxBytesMb and pdfMaxPages config
+- [Tools Overview](/tools) - all available agent tools
+- [Configuration Reference](/gateway/config-agents#agent-defaults) - pdfMaxBytesMb and pdfMaxPages config