fix inconsistent spacing in the doc (#576)

README.md

@@ -27,15 +27,14 @@ of the current project.
 
  Our CI pipeline builds and tests on following `x86-64` platforms:
 
-* ubuntu-18.04 ( Default GCC Compiler - 7.5.0 )
-* ubuntu-18.04 ( GCC 4.8 with -std=c++11 flag )
-* ubuntu-20.04 ( Default GCC Compiler - 9.3.0 with -std=c++20 flags )
-* macOS 10.15 ( Xcode 12.2 )
-* Windows Server 2019 (Visual Studio Enterprise 2019 )
+* ubuntu-18.04 (Default GCC Compiler - 7.5.0)
+* ubuntu-18.04 (GCC 4.8 with -std=c++11 flag)
+* ubuntu-20.04 (Default GCC Compiler - 9.3.0 with -std=c++20 flags)
+* macOS 10.15 (Xcode 12.2 )
+* Windows Server 2019 (Visual Studio Enterprise 2019)
 
 In general, the code shipped from this repository should build on all platforms having C++ compiler with [supported C++ standards](#supported-c-versions).
 
-
 ## Installation
 
 Please refer to [INSTALL.md](./INSTALL.md).