Fix docs about CodeSource.root_path (#1051)

Author: alexmojaki

docs/how-to-guides/link-to-code-source.md

@@ -13,14 +13,15 @@ logfire.configure(
     code_source=logfire.CodeSource(
         repository='https://github.com/pydantic/logfire',  #(1)!
         revision='<hash of commit used on release>',  #(2)!
-        root_path='/root/path',  #(3)!
+        root_path='path/within/repo',  #(3)!
     )
 )
 ```
 
 1. The URL of the repository e.g. `https://github.com/pydantic/logfire`.
 2. The specific branch, tag, or commit hash to link to e.g. `main`.
-3. The path to the root of the repository. If your code is in a subdirectory, you can specify it here.
+3. The path from the root of the repository to the current working directory of the process. If your code is in a
+   subdirectory of your repo, you can specify it here. Otherwise you can probably omit this.
 
 You can learn more in our [`logfire.CodeSource`][logfire.CodeSource] API reference.
 
@@ -32,7 +33,7 @@ For other OpenTelemetry SDKs, you can configure these settings using resource at
 ```
 OTEL_RESOURCE_ATTRIBUTES=vcs.repository.url.full=https://github.com/pydantic/platform
 OTEL_RESOURCE_ATTRIBUTES=${OTEL_RESOURCE_ATTRIBUTES},vcs.repository.ref.revision=main
-OTEL_RESOURCE_ATTRIBUTES=${OTEL_RESOURCE_ATTRIBUTES},vcs.root.path=.
+OTEL_RESOURCE_ATTRIBUTES=${OTEL_RESOURCE_ATTRIBUTES},vcs.root.path=path/within/repo
 ```
 
 [otel-resource-attributes]: https://opentelemetry.io/docs/specs/otel/configuration/sdk-environment-variables/#general-sdk-configuration

logfire/_internal/config.py

@@ -254,7 +254,7 @@ class CodeSource:
     """The git revision of the code e.g. branch name, commit hash, tag name etc."""
 
     root_path: str = ''
-    """The root path for the source code in the repository.
+    """The path from the root of the repository to the current working directory of the process.
 
     If you run the code from the directory corresponding to the root of the repository, you can leave this blank.