README: Update the Getting Started section (jsc#PED-5021)
    
    * Drop a mention that Git > 1.5.x is needed. This version was released
      in 2007 already.
    * Capitalize names of Git, Quilt and RPM, where appropriate.
    * Remove the use of the --quilt option from the sequence-patch.sh
      example as it is the default.
    * Replace patches.fixes/ with patches.suse/ since the latter is now the
      common directory for fix patches.
    * Fix some typos and avoid use of a serial comma.