Add Arch package and prebuilt TDLib support

README.md

@@ -18,6 +18,8 @@ A minimal Telegram terminal client built with `ncurses` and TDLib.
 - TDLib build dependencies (`gperf`, `openssl`, `zlib`, `git`)
 
 The project vendors TDLib automatically by default. If you already have TDLib installed with CMake package metadata, configure with `-DTELEGRAM_TUI_USE_SYSTEM_TDLIB=ON`.
+If you have a prebuilt TDLib bundle with `include/` and `lib/`, configure with
+`-DTELEGRAM_TUI_TDLIB_ROOT=/path/to/tdlib`.
 
 ## Build
 
@@ -26,9 +28,14 @@ cmake -S . -B build
 cmake --build build -j
 ```
 
+During configure, CMake also checks the app config at
+`$XDG_DATA_HOME/telegram-tui/config.json` or `~/.local/share/telegram-tui/config.json`.
+If that file contains `api_id` and `api_hash`, they are embedded into the build.
+
 ## Run
 
-Create a Telegram application at <https://my.telegram.org/apps>, then either export credentials:
+Create a Telegram application at <https://my.telegram.org/apps>, then either rely on the
+embedded credentials from the app config above, or export credentials:
 
 ```bash
 export TELEGRAM_API_ID=123456