Fix spelling/wording issues

Found by using:
    codespell --builtin clear,rare,usage,informal,code,names

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

README.md

@@ -6,7 +6,7 @@ Xorg mailing list:
 
   https://lists.x.org/mailman/listinfo/xorg
 
-The master development code repository can be found at:
+The primary development code repository can be found at:
 
   https://gitlab.freedesktop.org/xorg/lib/libdmx
 

configure.ac

@@ -39,7 +39,7 @@ XORG_MACROS_VERSION(1.8)
 XORG_DEFAULT_OPTIONS
 XORG_CHECK_MALLOC_ZERO
 
-# Obtain compiler/linker options for depedencies
+# Obtain compiler/linker options for dependencies
 PKG_CHECK_MODULES(DMX, [x11 >= 1.6] xext xextproto [dmxproto >= 2.2.99.1])
 
 AC_CONFIG_FILES([Makefile