Improve entry point lookup function documentation (#6451)

* Document that findEntryPointByName is not applicable if there is no [shader(...)] attribute

* Update the user guide to mention findAndCheckEntryPoint for entry points without [shader(...)] attributes

* format code

---------

Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>
Co-authored-by: Yong He <yonghe@outlook.com>

Author: 3 people

docs/user-guide/02-conventional-features.md

@@ -655,6 +655,7 @@ In this example, the `vertexMain` shader indicates that it is meant for the `ver
 Rasterization, compute, and ray-tracing pipelines each define their own stages, and new versions of graphics APIs may introduce new stages.
 
 For compatibility with legacy codebases, Slang supports code that leaves off `[shader(...)]` attributes; in these cases application developers must specify the names and stages for their entry points via explicit command-line or API options.
+Such entry points will not be found via `IModule::findEntryPointByName()`. Instead `IModule::findAndCheckEntryPoint()` must be used, and a stage must be specified.
 It is recommended that new codebases always use `[shader(...)]` attributes both to simplify their workflow, and to make code more explicit and "self-documenting."
 
 > #### Note ####

include/slang.h

@@ -4361,6 +4361,10 @@ struct IModule : public IComponentType
 {
     SLANG_COM_INTERFACE(0xc720e64, 0x8722, 0x4d31, {0x89, 0x90, 0x63, 0x8a, 0x98, 0xb1, 0xc2, 0x79})
 
+    /// Find and an entry point by name.
+    /// Note that this does not work in case the function is not explicitly designated as an entry
+    /// point, e.g. using a `[shader("...")]` attribute. In such cases, consider using
+    /// `IModule::findAndCheckEntryPoint` instead.
     virtual SLANG_NO_THROW SlangResult SLANG_MCALL
     findEntryPointByName(char const* name, IEntryPoint** outEntryPoint) = 0;