Clarify documentation for -fpie and -fPIE

	* doc/invoke.texi (-fpie, -fPIE): Fix grammar and clarify
	interaction with -pie.

From-SVN: r259774

gcc/ChangeLog

+2018-04-30  Jonathan Wakely  <jwakely@redhat.com>
+
+	* doc/invoke.texi (-fpie, -fPIE): Fix grammar and clarify
+	interaction with -pie.
+
 2018-04-30  David Malcolm  <dmalcolm@redhat.com>
 
 	* selftest.h: Fix alphabetization of per-source-file selftest

gcc/doc/invoke.texi

@@ -13094,10 +13094,10 @@ are defined to 2.
 @itemx -fPIE
 @opindex fpie
 @opindex fPIE
-These options are similar to @option{-fpic} and @option{-fPIC}, but
-generated position independent code can be only linked into executables.
-Usually these options are used when @option{-pie} GCC option is
-used during linking.
+These options are similar to @option{-fpic} and @option{-fPIC}, but the
+generated position-independent code can be only linked into executables.
+Usually these options are used to compile code that will be linked using
+the @option{-pie} GCC option.
 
 @option{-fpie} and @option{-fPIE} both define the macros
 @code{__pie__} and @code{__PIE__}.  The macros have the value 1