[doc] Simplify the build args description (#798)

Author: aobolensk

docs/user_guide/build.rst

@@ -7,13 +7,13 @@ Navigate to the project root.
 
    .. code-block:: bash
 
-      cmake -S . -B build -D USE_FUNC_TESTS=ON -D USE_PERF_TESTS=ON -D CMAKE_BUILD_TYPE=Release
+      cmake -S . -B build
 
    To configure only selected tasks:
 
    .. code-block:: bash
 
-      cmake -S . -B build -DPPC_TASKS="example_threads;example_processes" -D USE_FUNC_TESTS=ON -D USE_PERF_TESTS=ON -D CMAKE_BUILD_TYPE=Release
+      cmake -S . -B build -DPPC_TASKS="example_threads;example_processes"
 
    Optional: enable sanitizers for local debugging
 

docs/user_guide/ci.rst

@@ -102,7 +102,7 @@ clang-tidy (static analysis):
 
    # Configure with compile_commands.json
    cmake -S . -B build -G Ninja -D CMAKE_BUILD_TYPE=Release -D CMAKE_EXPORT_COMPILE_COMMANDS=ON
-   cmake --build build -j
+   cmake --build build --parallel
 
    # clang-tidy run:
    ### analyze all sources
@@ -116,14 +116,14 @@ gcovr (coverage, GCC):
 
    # Configure with coverage flags (use GCC)
    cmake -S . -B build -G Ninja -D USE_COVERAGE=ON -D CMAKE_BUILD_TYPE=Release
-   cmake --build build -j
+   cmake --build build --parallel
 
    # Run tests here (threads/processes/performance)
    scripts/run_tests.py --running-type=threads --counts 1 2 4
 
    # Generate reports (install gcovr if needed: python3 -m pip install gcovr)
    mkdir -p cov-report
-   (cd build && gcovr --gcov-executable "$(which gcov-14 || which gcov)" \
+   (cd build && gcovr --gcov-executable "$(which gcov)" \
          -r ../ \
          --exclude '.*3rdparty/.*' \
          --exclude '/usr/.*' \