docs/reference: introduce the cue command page

This adds an introduction to docs/reference/command/, explaining the
guides and list of sub-commands found on the page. It also presents a
one-line intro for each page section.

Closes cue-lang/docs-and-content#198.

Preview-Path: /docs/reference/command/
Signed-off-by: Jonathan Matthews <[email protected]>
Change-Id: Ife26896c8635389e00ae971b12dad55964b4a443
Dispatch-Trailer: {"type":"trybot","CL":1208783,"patchset":6,"ref":"refs/changes/83/1208783/6","targetBranch":"master"}

content/docs/reference/command/_en.md

@@ -2,11 +2,31 @@
 title: The cue command
 weight: 50
 toc_hide: false
-aliases: [/docs/reference/cli]
 ---
 
+The `cue` command is a versatile interface for working with CUE and its ecosystem.
+It provides a variety of sub-commands, including tools
+for [validating]({{<relref"cue-help-vet">}}),
+[importing]({{<relref"cue-help-import">}}), and
+[exporting]({{<relref"cue-export">}}) data and constraints;
+for running
+[data-driven workflows]({{<relref"cue-help-commands">}});
+and for working with dependencies via
+[CUE modules]({{<relref"cue-help-modules">}}) and
+[module registries]({{<relref"cue-help-registryconfig">}}).
+
+On this page you can find [the full list of sub-commands](#help-texts)
+in the latest version of `cue`, and their built-in help texts.
+You'll also find an incomplete-but-expanding set of guides dedicated to
+[the most commonly-used sub-commands](#guides).
+These guides include curated links to related content, including how-to guides,
+tutorials and other relevant documentation.
+
+<!-- H3 heading so this *doesn't* show up in the left-hand nav, which can serve as a command index. -->
 ### Guides
 
+Dedicated guides for common `cue` sub-commands:
+
 {{<cards>}}
 {{< card
     href="cue-export/"
@@ -17,8 +37,9 @@ configurations encoded in formats like JSON or YAML.
 {{</card>}}
 {{</cards>}}
 
+<!-- H3 heading so this *doesn't* show up in the left-hand nav, which can serve as a command index. -->
 ### Help texts
 
-The `cue help` command displays a help text for every `cue` subcommand.
-If a guide is not yet available for a particular command (above)
-then refer to the related help text in this list:
+The built-in help texts available in the
+[latest version]({{<relref"docs/introduction/installation">}}#installing-the-cue-command)
+of `cue`:

hugo/content/en/docs/reference/command/_index.md

@@ -2,11 +2,31 @@
 title: The cue command
 weight: 50
 toc_hide: false
-aliases: [/docs/reference/cli]
 ---
 
+The `cue` command is a versatile interface for working with CUE and its ecosystem.
+It provides a variety of sub-commands, including tools
+for [validating]({{<relref"cue-help-vet">}}),
+[importing]({{<relref"cue-help-import">}}), and
+[exporting]({{<relref"cue-export">}}) data and constraints;
+for running
+[data-driven workflows]({{<relref"cue-help-commands">}});
+and for working with dependencies via
+[CUE modules]({{<relref"cue-help-modules">}}) and
+[module registries]({{<relref"cue-help-registryconfig">}}).
+
+On this page you can find [the full list of sub-commands](#help-texts)
+in the latest version of `cue`, and their built-in help texts.
+You'll also find an incomplete-but-expanding set of guides dedicated to
+[the most commonly-used sub-commands](#guides).
+These guides include curated links to related content, including how-to guides,
+tutorials and other relevant documentation.
+
+<!-- H3 heading so this *doesn't* show up in the left-hand nav, which can serve as a command index. -->
 ### Guides
 
+Dedicated guides for common `cue` sub-commands:
+
 {{<cards>}}
 {{< card
     href="cue-export/"
@@ -17,8 +37,9 @@ configurations encoded in formats like JSON or YAML.
 {{</card>}}
 {{</cards>}}
 
+<!-- H3 heading so this *doesn't* show up in the left-hand nav, which can serve as a command index. -->
 ### Help texts
 
-The `cue help` command displays a help text for every `cue` subcommand.
-If a guide is not yet available for a particular command (above)
-then refer to the related help text in this list:
+The built-in help texts available in the
+[latest version]({{<relref"docs/introduction/installation">}}#installing-the-cue-command)
+of `cue`: