web: strip down indices for tutorials, use-cases and user-guide

per #903 (review)

public/static/docs/sidebar.json

@@ -52,7 +52,7 @@
   },
   {
     "slug": "tutorials",
-    "source": false,
+    "source": "tutorials/index.md",
     "children": [
       {
         "slug": "interactive",

public/static/docs/tutorials/index.md

@@ -0,0 +1,10 @@
+# Tutorials
+
+Beyond the _Get Started_ guide, our tutorials provide similarly reproducible
+walkthroughs on more advanced topics. They also come in different formats such
+as the [interactive](/doc/tutorials/interactive) ones (to try and learn DVC
+without installing it), and from different sources like our official ones and
+those produced by the DVC [community](/doc/tutorials/community).
+
+Please choose from the navigation sidebar to the left, or click the `Next`
+button below ↘

public/static/docs/tutorials/interactive.md

@@ -2,6 +2,7 @@
 
 Interactive lessons and tutorials on [Katacoda](https://katacoda.com/dvc) that
 explain the basic concepts of DVC and show how to use it in simple ML scenarios.
+Try and learn DVC without having to install it locally!
 
 ## Basic Concepts
 

public/static/docs/use-cases/index.md

@@ -1,29 +1,15 @@
 # Use Cases
 
 We provide short articles on common ML workflow or data management scenarios
-that DVC can help with or improve. These include a justified context (usually
-extracted from real-life cases), and the approaches to solving them combine
-several features and commands of DVC, as well as other appropriate tools. They
-range from basic to more advanced:
-
-- [Data Versioning](/doc/use-cases/versioning-data-and-model-files) describes
-  our most primary use: tracking and versioning large files with Git + DVC.
-- [Sharing Data and Model Files](/doc/use-cases/sharing-data-and-model-files)
-  goes over the basic collaboration possibilities enabled by DVC.
-- [Shared Development Server](/doc/use-cases/shared-development-server) provides
-  instructions to setup a single development machine for teams that prefer so.
-- [Data Registries](/doc/use-cases/data-registries) explains how to use a
-  <abbr>DVC repository<abbr> as a shared hub for reusing datasets or models
-  among several projects.
-
-> This list of use cases is **not** exhaustive. We keep reviewing our docs and
-> will include interesting scenarios that surface in the community. Please,
-> [contact us](/support) if you need help or have suggestions!
-
-Use cases are not written to be run end-to-end. For more general, hands-on
-experience with DVC, we recommend following the [Get Started](/doc/get-started),
-and/or [Tutorials](/doc/tutorials) first. These include prepared datasets,
-source code files, and example commands that can be copied and pasted into
-terminal. These use cases also link to our more general
-[User Guide](/doc/user-guide), and technical
-[command references](/doc/command-reference).
+that DVC can help with or improve. These include the motivating context (usually
+extracted from real-life cases); And the approaches to solving them can combine
+several features of DVC. Use cases are not written to be run end-to-end. For
+more general, hands-on experience with DVC, we recommend following the
+[Get Started](/doc/get-started), and/or [Tutorials](/doc/tutorials) first.
+
+> We keep reviewing our docs and will include interesting scenarios that surface
+> in the community. Please, [contact us](/support) if you need help or have
+> suggestions!
+
+Our use cases range from basic to more advanced. Please choose from the
+navigation sidebar to the left, or click the `Next` button below ↘

public/static/docs/user-guide/index.md

@@ -8,28 +8,5 @@ of DVC, to more advanced and specific things you can do. We also include a few
 guides related to contributing to this
 [open-source project](https://github.com/iterative/dvc).
 
-- [DVC Files and Directories](/doc/user-guide/dvc-files-and-directories)
-  describes the internal `.dvc/` directory and it's contents.
-- [DVC-File Format](/doc/user-guide/dvc-file-format) explains how the special
-  metafiles that DVC creates to track <abbr>project</abbr> data are constructed.
-- [Dvcignore](/doc/user-guide/dvcignore) explains how to exclude files from DVC
-  operations with the optional `.dvcignore` file.
-- [Update a Tracked File](/doc/use-cases/updating-tracked-files) explains how to
-  modify protected data under DVC control (related to the `cache.type` option of
-  DVC).
-- [Large Dataset Optimization](/doc/user-guide/large-dataset-optimization)
-  covers the topic of how <abbr>caches</abbr> data can be automatically file
-  linked to the workspace to avoid duplication of storage or slow and
-  unnecessary file operations.
-- [External Dependencies](/doc/user-guide/external-dependencies) goes over the
-  ways in which DVC can keep track of files external to the project (or even
-  remote on a network or cloud location) as
-  [DVC-file](/doc/user-guide/dvc-files-and-directories) dependencies.
-- [Managing External Data](/doc/user-guide/managing-external-data) explains both
-  external outputs and external cache.
-- [Contributing](/doc/user-guide/contributing) is related with getting involved
-  directly in developing DVC. Contributors are very welcomed in our
-  [community](/support)!
-
-The remaining guides are about optional productivity enhancements and other tips
-and tools related to advanced usage of DVC.
+Please choose from the navigation sidebar to the left, or click the `Next`
+button below ↘