Cleaned up building instructions

BUILDING.md

@@ -24,27 +24,30 @@ $ cd build
 $ make -j2
 ```
 
-### Apple macOS with XCode project
+### Apple macOS with Xcode project
+
+To generate an Xcode project in the `build` directory:
 
 ```bash
-$ cmake -B "$BUILD_DIR" -DUSE_GNUTLS=0 -DUSE_NICE=0 -G Xcode
+$ cmake -B build -DUSE_GNUTLS=0 -DUSE_NICE=0 -G Xcode
 ```
 
-The XCode project is generated in `build` directory.
-
 #### Solving "Could NOT find OpenSSL" error
 
-You need to add OpenSSL root directory if your build fails with the following message:
+You need to add OpenSSL root directory if the build fails with the following message:
+
 ```
 Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the system variable OPENSSL_ROOT_DIR (missing: OPENSSL_CRYPTO_LIBRARY OPENSSL_INCLUDE_DIR)
 ```
 
 For example:
+
 ```bash
 $ cmake -B build -DUSE_GNUTLS=0 -DUSE_NICE=0 -G Xcode -DOPENSSL_ROOT_DIR=/usr/local/Cellar/openssl\@1.1/1.1.1h/
 ```
 
 ### Microsoft Windows with MinGW cross-compilation
+
 ```bash
 $ cmake -B build -DCMAKE_TOOLCHAIN_FILE=/usr/share/mingw/toolchain-x86_64-w64-mingw32.cmake # replace with your toolchain file
 $ cd build
@@ -52,6 +55,7 @@ $ make -j2
 ```
 
 ### Microsoft Windows with Microsoft Visual C++
+
 ```bash
 $ cmake -B build -G "NMake Makefiles"
 $ cd build