Algorithm selection clarification

Resolves: open-quantum-safe#1781
Signed-off-by: Dmitry Belyavskiy <beldmit@gmail.com>

CONFIGURE.md

@@ -58,6 +58,8 @@ For a full list of such options and their default values, consult [.CMake/alg_su
 
 Selects algorithm set enabled. Possible values are "STD" selecting all algorithms standardized by NIST; "NIST_R4" selecting all algorithms evaluated in round 4 of the NIST PQC competition; "All" (or any other value) selecting all algorithms integrated into liboqs. Parameter setting "STD" minimizes library size but may require re-running code generator scripts in projects integrating `liboqs`; e.g., [oqs-provider](https://github.com/open-quantum-safe/oqs-provider) and [oqs-boringssl](https://github.com/open-quantum-safe/boringssl).
 
+**Attention**: If you use any predefined value (`STD` or `NIST_R4` as of now) for this variable, the values added via [OQS_ENABLE_KEM_ALG/OQS_ENABLE_SIG_ALG](#OQS_ENABLE_KEM_ALG/OQS_ENABLE_SIG_ALG) variables will be ignored.
+
 **Default**: `All`.
 
 ## OQS_BUILD_ONLY_LIB