DOC: Add troubleshooting hint for manual cpp standard

doc/README_SETUP.md

@@ -74,6 +74,13 @@ dependencies.
 Depending on the clang version it might be necessary to use additionally the following flag:
 `-DCMAKE_CXX_FLAGS="-Wno-unused-parameter"`
 
+#### conan uses outdated cppstd during install
+
+If you experience compiler errors during a `conan install` process due
+to, e.g., `std::string_view` being unavailable, try specifying the cpp
+standard manually by `conan install .. [other options] -s
+"compiler.cppstd=17"`.
+
 ## Unit Tests
 
 ### Build
@@ -83,10 +90,10 @@ For the tests there is a slightly different setup required (with option `-D CMAK
 1. `mkdir build && cd build/`
 2. `conan install .. -s "compiler.libcxx=libstdc++11"`
 3. `cmake -B . -D CMAKE_BUILD_TYPE=Debug ..`
-   * If your clang-format version is too old, formatting, linting etc. can be skipped:  
-     `cmake -B . -D CMAKE_BUILD_TYPE=Debug -D SKIP_LINTING=ON ..`
+   * If your clang-format version is too old, formatting, linting etc. can be skipped:
+	 `cmake -B . -D CMAKE_BUILD_TYPE=Debug -D SKIP_LINTING=ON ..`
    * Depending on the clang version it might be necessary to also add
-     `-DCMAKE_CXX_FLAGS="-Wno-unused-parameter"`
+	 `-DCMAKE_CXX_FLAGS="-Wno-unused-parameter"`
 5. `cmake --build .`
 
 ### Run