docugen: walk past private snake_case helpers so the doc lands on the public macro

DocuGen attached a doc-comment block to whichever symbol came right
after it. The Phase 2 / R2 Str-overload work introduced a recurring
shape where the public surface lives in a MISRA_OVERLOAD + _Generic
macro stack that sits BELOW the snake_case implementation helpers:

    /// doc block
    T snake_zstr(...);
    T snake_str(...);
    #define PascalName(...) MISRA_OVERLOAD(PascalName, __VA_ARGS__)
    #define PascalName_1(...) _Generic(...)
    #define PascalName_2(...) _Generic(...)

The previous logic landed the doc on snake_zstr (which is private and
therefore dropped), then broke out of the search. Result: BitVecFromStr,
IntFromStr, FloatFromStr, SocketAddrParse, KvConfigGet[*],
HttpRequestParse, MachoCacheResolve, and ~45 other public macros never
made it into the generated site.

Fix: treat 'private' the same as 'plumbing' in the per-block walk --
skip the declaration and keep looking for a public symbol to attach
to (numbered MISRA_OVERLOAD arms already did this). The natural
blank-line boundary still terminates the search, so docs only attach
to the directly-following public-API stack.

Confirmed by running DocuGen on Include/Misra/Std/Container/BitVec:
generated-doc-BitVecFromStr.md and generated-doc-BitVecTryFromStr.md
now appear with the right description, parameters, and tags. Full-tree
run produces 1141 docs vs. ~1090 before, with the formerly-missing
overloaded APIs now indexed.

Author: brightprogrammer

Scripts/DocuGen.py

@@ -256,10 +256,25 @@ def extract_symbols_and_store_content(file_path: Path):
 
                     symbol_name, inferred_kind = symbol_info
                     internal_reason = internal_documentation_symbol_reason(symbol_name)
-                    if internal_reason == "private":
-                        line_index = definition_index + declaration_line_count
-                        break
-                    if internal_reason == "plumbing":
+                    # Walk past both `private` (snake_case impl helpers) and
+                    # `plumbing` (numbered MISRA_OVERLOAD arms, `_HAS_ARGS`,
+                    # etc.) until either a public PascalCase symbol absorbs
+                    # the doc block or the run of non-blank declarations
+                    # ends. The Phase-2 / R2 pattern is:
+                    #
+                    #     /// doc block
+                    #     T snake_zstr(...);
+                    #     T snake_str(...);
+                    #     #define PascalName(...) MISRA_OVERLOAD(PascalName, ...)
+                    #     #define PascalName_1(...) _Generic(...)
+                    #     #define PascalName_2(...) _Generic(...)
+                    #
+                    # where the public surface is `PascalName` and the doc
+                    # is meant for it; the snake_case decls are skipped and
+                    # the numbered overloads are plumbing. Treating private
+                    # the same as plumbing lets the doc walk past both to
+                    # land on PascalName.
+                    if internal_reason in ("private", "plumbing"):
                         definition_index += declaration_line_count
                         continue