Split app developer guide into how-to

Signed-off-by: Natalie Arellano <[email protected]>

Author: Natalie Arellano

content/docs/app-developer-guide/_index.md

@@ -0,0 +1,6 @@
++++
+title="Configure build inputs"
+weight=1
+expand=false
+include_summaries=true
++++

content/docs/for-app-developers/how-to/build-inputs/_index.md

@@ -1,7 +1,7 @@
 +++
-title="Environment variables"
-weight=3
-summary="Environment variables are a common way to configure various buildpacks at build-time."
+title="Configure build-time environment variables"
+weight=2
+summary="Customize buildpack behavior through the build-time environment."
 +++
 <!--+- `
 # Environment variables

content/docs/app-developer-guide/environment-variables.md renamed to content/docs/for-app-developers/how-to/build-inputs/configure-build-time-environment.md

@@ -1,7 +1,7 @@
 +++
-title="Mounting Volumes"
-weight=4
-summary="Volumes are a mechanism for both supplying and persisting data generated by build containers."
+title="Mount volumes at build-time"
+weight=3
+summary="Supply and persist data from build containers with arbitrary volume mounts."
 +++
 <!--+if false+-->
 {{< param "summary" >}}

content/docs/app-developer-guide/mounting-volumes.md renamed to content/docs/for-app-developers/how-to/build-inputs/mount-volumes.md

@@ -1,16 +1,17 @@
 +++
-title="Specify buildpacks"
-weight=4
-summary="Learn how to specify exactly what buildpacks are used during the build process."
+title="Specify buildpacks or extensions at build time"
+weight=1
+summary="No builder author can be truly omniscient, and whoever created yours surely was no exception!"
 +++
+
 <!--+- `
 # Specify buildpacks
 `+-->
 
 You may specify exactly what buildpacks are used during the build process by referencing them with a URI in any of the following formats.
 
 | Type                  | Format                                       |
-| --------------------- | -------------------------------------------- |
+|-----------------------|----------------------------------------------|
 | Relative              | `<path>`                                     |
 | Filesystem            | `file://[<host>]/<path>`                     |
 | URL                   | `http[s]://<host>/<path>`                    |
@@ -50,7 +51,11 @@ pack build sample-java-maven-app \
 > - `--buildpack` multiple times, or
 > - a comma-separated list to `--buildpack` (without spaces)
 
+Similarly, it is possible to provide extensions at build time:
 
+```bash
+pack build [...] --extension=foo [...]`
+```
 
 ## Using a Project Descriptor
 

content/docs/app-developer-guide/specify-buildpacks.md renamed to content/docs/for-app-developers/how-to/build-inputs/specify-buildpacks-from-cli.md

@@ -1,7 +1,7 @@
 +++
-title="Cache Images"
-weight=4
-summary="Learn how to use cache-images to share cached layers"
+title="Use a cache image"
+weight=6
+summary="Share layers between builds with a cache image."
 +++
 <!--+- `
 # Cache Images
@@ -10,7 +10,6 @@ summary="Learn how to use cache-images to share cached layers"
 Cache Images are a way to preserve build optimizing layers across different host machines. 
 These images can improve performance when using `pack` in ephemeral environments such as CI/CD pipelines.
 
-
 ## Using Cache Images (`--cache-image`)
 
 The `--cache-image` parameter must be in the following format

content/docs/app-developer-guide/using-cache-image.md renamed to content/docs/for-app-developers/how-to/build-inputs/use-cache-image.md

@@ -1,7 +1,7 @@
 +++
-title="Using Inline Buildpacks"
-weight=7
-summary="Learn how to create an ephemeral buildpack to customize your build."
+title="Use an inline buildpack"
+weight=5
+summary="Customize your build with a bit of shell script."
 +++
 
 You can supplement your app's build process with custom scripts by creating an _inline buildpack_. An inline buildpack is an ephemeral buildpack that's defined in your [project descriptor][project-toml] (i.e. `project.toml`). You can include a script to run as part of the build without setting up all the files and directories that are required for a complete buildpack.

content/docs/app-developer-guide/using-inline-buildpacks.md renamed to content/docs/for-app-developers/how-to/build-inputs/use-inline-buildpacks.md

@@ -1,7 +1,7 @@
 +++
-title="Using project.toml"
-weight=6
-summary="Learn how to use a project.toml file to simplify configuring pack."
+title="Use project.toml"
+weight=4
+summary="Simplify your `pack` configuration."
 +++
 
 A `project descriptor` (alternatively referred to as a `project.toml` file) allows users to detail configuration for a

content/docs/app-developer-guide/using-project-descriptor.md renamed to content/docs/for-app-developers/how-to/build-inputs/use-project-toml.md

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++++
+title="Understand build outputs"
+weight=2
+expand=false
+include_summaries=true
++++