COMMANDS.md: Add commands from `pyenv --help`
COMMANDS.md: Add commands from `pyenv --help`

dongguangming/pyenv,UCASREN/pyenv,lozybean/pyenv,rowhit/pyenv,dnsd/pyenv,pyenv/pyenv,habinmusic/pyenv,genome-vendor/pyenv,kevinburke/pyenv,recruit-mtl/pyenv,lepture/pyenv,BanzaiMan/pyenv,sebhahn/pyenv,lozybean/pyenv,takluyver/pyenv,yyuu/pyenv,VShangxiao/pyenv,takluyver/pyenv,pyenv/pyenv,genome-vendor/pyenv,UCASREN/pyenv,xshwy/pyenv,sebhahn/pyenv,hlecuanda/pyenv,lepture/pyenv,kevinburke/pyenv,BanzaiMan/pyenv,yeonsh/pyenv,fly19890211/pyenv,cehoffman/pyenv,dnsd/pyenv,dongguangming/pyenv,pyenv/pyenv,rowhit/pyenv,zmwangx/pyenv,obimod/pyenv,xshwy/pyenv,syndbg/goenv,sebhahn/pyenv,chenfengyuan/pyenv,yeonsh/pyenv,yyuu/pyenv,syndbg/goenv,VShangxiao/pyenv,recruit-mtl/pyenv,hlecuanda/pyenv,habinmusic/pyenv,chenfengyuan/pyenv,syndbg/goenv,fly19890211/pyenv,cehoffman/pyenv,syndbg/goenv,zmwangx/pyenv,obimod/pyenv