docs/system: Fix grammar in documentation

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20200827173051.31050-1-sw@weilnetz.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

docs/system/build-platforms.rst

@@ -57,12 +57,12 @@ macOS
 -----
 
 The project supports building with the two most recent versions of
-macOS, with the current homebrew package set available.
+macOS, with the current Homebrew package set available.
 
 FreeBSD
 -------
 
-The project aims to support the all the versions which are not end of
+The project aims to support all versions which are not end of
 life.
 
 NetBSD
@@ -75,5 +75,5 @@ new major version is released.
 OpenBSD
 -------
 
-The project aims to support the all the versions which are not end of
+The project aims to support all versions which are not end of
 life.