README: Move to "meson setup [options]"

Fixes the warning:
WARNING: Running the setup command as `meson [options]` instead of
`meson setup [options]` is ambiguous and deprecated.

Tested: The following work:
meson setup builddir
ninja -C builddir

Change-Id: Idc8a5941e68dfe62395d9751a6c9cc3f3622ee0a
Signed-off-by: Pavithra Barithaya <pavithra.b@ibm.com>
diff --git a/README.md b/README.md
index 1475024..4722680 100644
--- a/README.md
+++ b/README.md
@@ -13,21 +13,21 @@
 - Compile phosphor-time-manager with default options:
 
   ```
-     meson builddir
+     meson setup builddir
      ninja -C builddir
   ```
 
 - Compile phosphor-time-manager with some configurable options:
 
   ```
-     meson builddir -Dbuildtype=minsize  -Dtests=disabled
+     meson setup builddir -Dbuildtype=minsize  -Dtests=disabled
      ninja -C builddir
   ```
 
 - Generate test coverage report:
 
   ```
-     meson builddir -Db_coverage=true -Dtests=enabled
+     meson setup builddir -Db_coverage=true -Dtests=enabled
      ninja coverage -C builddir test
   ```