Docs: retroactively update 1.89 changelog/docs to clarify that strong typing ImGuiKey was technically a breaking change for users of legacy indices. (#4921)

Amend 4b522e145

docs/CHANGELOG.txt

@@ -95,6 +95,11 @@ Breaking changes:
   Without '#define IMGUI_DISABLE_OBSOLETE_FUNCTIONS' this will silently be fixed until we obsolete it.
   (This incorrect pattern has been mentioned or suggested in: #4510, #3355, #1760, #1490, #4152, #150,
    threads have been amended to refer to this issue).
+- Inputs: ImGuiKey is now a typed enum, allowing ImGuiKey_XXX symbols to be named in debuggers. (#4921)
+  This will require uses of legacy backend-dependent indices to be casted, e.g.
+   - with imgui_impl_glfw:  IsKeyPressed(GLFW_KEY_A) -> IsKeyPressed((ImGuiKey)GLFW_KEY_A);
+   - with imgui_impl_win32: IsKeyPressed('A')        -> IsKeyPressed((ImGuiKey)'A')
+   - etc. however if you are upgrading code you might as well use the backend-agnostic IsKeyPressed(ImGuiKey_A) now.
 - Renamed and merged keyboard modifiers key enums and flags into a same set:  (#4921, #456)
    - ImGuiKey_ModCtrl  and ImGuiModFlags_Ctrl  -> ImGuiMod_Ctrl
    - ImGuiKey_ModShift and ImGuiModFlags_Shift -> ImGuiMod_Shift
@@ -223,7 +228,6 @@ Other Changes:
 - ImDrawList: Not using alloca() anymore, lift single polygon size limits. (#5704, #1811)
 - Platform IME: [Windows] Removed call to ImmAssociateContextEx() leading to freeze on some setups.
   (#2589, #5535, #5264, #4972)
-- Misc: ImGuiKey is now a typed enum, allowing ImGuiKey_XXX symbols to be named in debuggers. (#4921)
 - Misc: better error reporting for PopStyleColor()/PopStyleVar() + easier to recover. (#1651)
 - Misc: io.Framerate moving average now converge in 60 frames instead of 120. (#5236, #4138)
 - Debug Tools: Debug Log: Visually locate items when hovering a 0xXXXXXXXX value. (#5855)

imgui.cpp

@@ -395,6 +395,11 @@ CODE
                        the ImGuiKey_ModXXX were introduced in 1.87 and mostly used by backends.
                        the ImGuiModFlags_XXX have been exposed in imgui.h but not really used by any public api only by third-party extensions.
                        exceptionally commenting out the older ImGuiKeyModFlags_XXX names ahead of obsolescence schedule to reduce confusion and because they were not meant to be used anyway.
+ - 2022/09/20 (1.89) - ImGuiKey is now a typed enum, allowing ImGuiKey_XXX symbols to be named in debuggers.
+                       this will require uses of legacy backend-dependent indices to be casted, e.g.
+                          - with imgui_impl_glfw:  IsKeyPressed(GLFW_KEY_A) -> IsKeyPressed((ImGuiKey)GLFW_KEY_A);
+                          - with imgui_impl_win32: IsKeyPressed('A')        -> IsKeyPressed((ImGuiKey)'A')
+                          - etc. However if you are upgrading code you might well use the better, backend-agnostic IsKeyPressed(ImGuiKey_A) now!
  - 2022/09/12 (1.89) - removed the bizarre legacy default argument for 'TreePush(const void* ptr = NULL)', always pass a pointer value explicitly. NULL/nullptr is ok but require cast, e.g. TreePush((void*)nullptr);
  - 2022/09/05 (1.89) - commented out redirecting functions/enums names that were marked obsolete in 1.77 and 1.78 (June 2020):
                          - DragScalar(), DragScalarN(), DragFloat(), DragFloat2(), DragFloat3(), DragFloat4(): For old signatures ending with (..., const char* format, float power = 1.0f) -> use (..., format ImGuiSliderFlags_Logarithmic) if power != 1.0f.