Update doc on profiling config settings (#49964)

Move profiler documentation from the runtime repo to the docs repo.
Add description of new possible environment variable names.

Fixes #49963

---------

Co-authored-by: Noah Falk <noahfalk@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Genevieve Warren <24882762+gewarren@users.noreply.github.com>

Author: 4 people

docs/core/runtime-config/debugging-profiling.md

@@ -9,6 +9,9 @@ This article details the settings you can use to configure .NET debugging and pr
 
 [!INCLUDE [complus-prefix](../../../includes/complus-prefix.md)]
 
+> [!NOTE]
+> Starting in .NET 11, profiler environment variables now support both `DOTNET` and `CORECLR` prefixes. The `DOTNET` prefix is the new standard, while `CORECLR` is maintained for backwards compatibility and might be removed in the future.
+
 ## Enable diagnostics
 
 - Configures whether the debugger, the profiler, and EventPipe diagnostics are enabled or disabled.
@@ -23,11 +26,12 @@ This article details the settings you can use to configure .NET debugging and pr
 
 - Configures whether profiling is enabled for the currently running process.
 - If you omit this setting, profiling is disabled. This is equivalent to setting the value to `0`.
+- To load a profiler, in addition to enabling profiling, the profiler GUID and profiler location also need to be configured using these settings.
 
 | | Setting name | Values |
 | - | - | - |
 | **runtimeconfig.json** | N/A | N/A |
-| **Environment variable** | `CORECLR_ENABLE_PROFILING` | `0` - disabled<br/>`1` - enabled |
+| **Environment variable** | `CORECLR_ENABLE_PROFILING` or `DOTNET_ENABLE_PROFILING` | `0` - disabled<br/>`1` - enabled |
 
 ## Profiler GUID
 
@@ -36,19 +40,28 @@ This article details the settings you can use to configure .NET debugging and pr
 | | Setting name | Values |
 | - | - | - |
 | **runtimeconfig.json** | N/A | N/A |
-| **Environment variable** | `CORECLR_PROFILER` | *string-guid* |
+| **Environment variable** | `CORECLR_PROFILER` or `DOTNET_PROFILER` | *string-guid* |
 
 ## Profiler location
 
+Once profiling is enabled, the profiler can be loaded in two ways: with environment variables (cross-plat) or through the registry (Windows only). The profiler path environment variables take precedence over any COM library path in the registry if both are specified.
+
+### Environment variable (cross-plat)
+
 - Specifies the path to the profiler DLL to load into the currently running process (or 32-bit or 64-bit process).
 - If more than one variable is set, the bitness-specific variables take precedence. They specify which bitness of profiler to load.
-- For more information, see [Finding the profiler library](https://github.com/dotnet/runtime/blob/main/docs/design/coreclr/profiling/Profiler%20Loading.md).
 
 | | Setting name | Values |
 | - | - | - |
-| **Environment variable** | `CORECLR_PROFILER_PATH` | *string-path* |
-| **Environment variable** | `CORECLR_PROFILER_PATH_32` | *string-path* |
-| **Environment variable** | `CORECLR_PROFILER_PATH_64` | *string-path* |
+| **Environment variable** | `CORECLR_PROFILER_PATH` or `DOTNET_PROFILER_PATH` | *string-path* |
+| **Environment variable** | `CORECLR_PROFILER_PATH_32` or `DOTNET_PROFILER_PATH_32` | *string-path* |
+| **Environment variable** | `CORECLR_PROFILER_PATH_64` or `DOTNET_PROFILER_PATH_64` | *string-path* |
+| **Environment variable** | `CORECLR_PROFILER_PATH_ARM32` or `DOTNET_PROFILER_PATH_ARM32` | *string-path* |
+| **Environment variable** | `CORECLR_PROFILER_PATH_ARM64` or `DOTNET_PROFILER_PATH_ARM64` | *string-path* |
+
+### Through the registry (Windows only)
+
+When the `DOTNET_PROFILER_PATH*` [environment variables](#environment-variable-cross-plat) aren't set while running on Windows, coreclr looks up the CLSID from `DOTNET_PROFILER` in the registry to find the full path to the profiler's DLL. Just like with any COM server DLL, the profiler's CLSID is looked up under HKEY_CLASSES_ROOT, which merges the classes from HKLM and HKCU.
 
 ## Export perf maps and jit dumps