Update telemetry file location

Signed-off-by: Josh W Lewis <josh.w.lewis@gmail.com>

text/0000-build-observability.md

@@ -66,9 +66,9 @@ Format](https://opentelemetry.io/docs/specs/otel/protocol/file-exporter/).
 
 In this solution, each lifecycle phase would write a `.jsonl` file with
 tracing data for that phase. For example, `lifecycle detector --telemetry`
-would write to `/layers/lifecycle-detect.jsonl`. Additionally each
+would write to `/layers/tracing/lifecycle/detect.jsonl`. Additionally each
 buildpack may also write tracing data to it's own `.jsonl` files (at
-`/layers/#{buildpack-id}@#{buildpack-version}.jsonl`).
+`/layers/tracing/buildpacks/#{id}@#{version}-#{phase}.jsonl`).
 
 These `.jsonl` files may be read by platform operators for consumption,
 transformation, enrichment, and/or export to an OpenTelemetry backend. Given
@@ -93,7 +93,7 @@ inherit `trace-id` and `parent-id` from platform systems.
 If `lifecycle` is provided the telemetry opt-in flag (such as `--telemetry`),
 `lifecycle` phases (such as `detect`, `build`, `export`) may emit an
 OpenTelemetry File Export with tracing data to a known location, such as
-`/layers/lifecycle-detect.jsonl` with contents like this:
+`/layers/tracing/lifecycle/detect.jsonl` with contents like this:
 
 ```json
 {
@@ -148,8 +148,8 @@ OpenTelemetry File Export with tracing data to a known location, such as
 
 ### Buildpack telemetry files
 
-During a buildpack's `detect` or `build` execution, a buildpack may emit
-an OpenTelemetry File Export with tracing data to `/layers/#{buildpack-id}@#{buildpack-version}.jsonl`
+During a buildpack's `detect` and/or `build` execution, a buildpack may emit
+an OpenTelemetry File Export with tracing data to `/layers/tracing/buildpacks/#{id}@#{version}-#{phase}.jsonl`
 with contents like this:
 
 ```json
@@ -202,6 +202,36 @@ with contents like this:
 }
 ```
 
+### Location
+
+All tracing files should be written to `/layers/tracing/`. Lifecycle execution
+traces should be written to `/layers/tracing/lifecycle/{phase}.jsonl`.
+Buildpack traces may be written to
+`/layers/tracing/buildpacks/{id}@{version}-{phase}.jsonl`.
+Extension traces may be written to
+`/layers/tracing/extensions/{id}@{version}-{phase}.jsonl`.
+
+A completed build with tracing might have a tracing file hierarchy like this:
+
+```
+<layers>
+└── tracing
+    ├── buildpacks
+    │   ├── other-id@other-version-detect.jsonl
+    │   ├── some-id@some-version-build.jsonl
+    │   └── some-id@some-version-detect.jsonl
+    ├── extensions
+    │   ├── some-id@some-version-detect.jsonl
+    │   └── some-id@some-version-generate.jsonl
+    └── lifecycle
+        ├── analyze.jsonl
+        ├── build.jsonl
+        ├── detect.jsonl
+        ├── export.jsonl
+        ├── extend.jsonl
+        └── restore.jsonl
+```
+
 ### Lifetime
 
 Telemetry files may be written at any point during the build, so that they