docs: the engineers' guide describes the compiler written in Finch

Rewritten (EN+PL): architecture, source tree, front end, code generation, C import and ABI, driver, bootstrapping and the
language server. The type, ownership and semantics sections are kept; the C++ function reference is gone (branch
before-bootstrap has that version).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015f73FesGZGYPkmDvUcj6QX

README.md

@@ -125,7 +125,7 @@ Pick the guide that fits you:
 | [`examples/vulkan.fch`](examples/vulkan.fch) | Vulkan: list the GPUs, their memory and queues, create a device |
 | [`examples/raylib.fch`](examples/raylib.fch) | raylib with C structs by value |
 | [`examples/llvm.fch`](examples/llvm.fch) | Finch building LLVM IR through the LLVM-C API |
-| [`boot/`](boot/) | the Finch compiler, written in Finch |
+| [`src/`](src/) | the compiler, written in Finch (the seed to build it is in [`bootstrap/`](bootstrap/)) |
 
 ## Roadmap
 

README.pl.md

@@ -125,7 +125,7 @@ Wybierz przewodnik dla siebie:
 | [`examples/vulkan.fch`](examples/vulkan.fch) | Vulkan: lista kart graficznych, ich pamięć i kolejki, tworzenie urządzenia |
 | [`examples/raylib.fch`](examples/raylib.fch) | raylib ze strukturami C przez wartość |
 | [`examples/llvm.fch`](examples/llvm.fch) | Finch budujący LLVM IR przez API LLVM-C |
-| [`boot/`](boot/) | kompilator Fincha napisany w Finchu |
+| [`src/`](src/) | kompilator napisany w Finchu (ziarno do jego zbudowania jest w [`bootstrap/`](bootstrap/)) |
 
 ## Plan rozwoju