Fix typo in DEVELOPMENT.md (#258)
Fix typo in DEVELOPMENT.md (#258)

(Change `scalars:scalars_demo` to `scalar:scalars_demo`.)
ioeric/tensorboard,qiuminxu/tensorboard,shakedel/tensorboard,francoisluus/tensorboard-supervise,ioeric/tensorboard,shakedel/tensorboard,tensorflow/tensorboard,agrubb/tensorboard,francoisluus/tensorboard-supervise,tensorflow/tensorboard,tensorflow/tensorboard,tensorflow/tensorboard,shakedel/tensorboard,francoisluus/tensorboard-supervise,qiuminxu/tensorboard,ioeric/tensorboard,shakedel/tensorboard,francoisluus/tensorboard-supervise,agrubb/tensorboard,francoisluus/tensorboard-supervise,tensorflow/tensorboard,francoisluus/tensorboard-supervise,tensorflow/tensorboard,tensorflow/tensorboard,qiuminxu/tensorboard,qiuminxu/tensorboard,shakedel/tensorboard,shakedel/tensorboard,agrubb/tensorboard,agrubb/tensorboard,qiuminxu/tensorboard,ioeric/tensorboard,agrubb/tensorboard,agrubb/tensorboard,qiuminxu/tensorboard,ioeric/tensorboard,ioeric/tensorboard