build: README punctuation pendantry

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

README

@@ -8,7 +8,7 @@
 This is the buildsystem for the OpenWrt Linux distribution.
 
 To build your own firmware you need a Linux, BSD or MacOSX system (case
-sensitive filesystem required)  Cygwin is unsupported because of the lack
+sensitive filesystem required). Cygwin is unsupported because of the lack
 of a case sensitive file system.
 
 You need gcc, binutils, bzip2, flex, python, perl, make, find, grep, diff,
@@ -23,7 +23,7 @@ packages into package/feeds/
 3. Run "make menuconfig" to select your preferred configuration for the
 toolchain, target system & firmware packages.
 
-4. Run "make" to build your firmware.  This will download all sources, build
+4. Run "make" to build your firmware. This will download all sources, build
 the cross-compile toolchain and then cross-compile the Linux kernel & all
 chosen applications for your target system.