improve everything

docs/index.md

docs/pages/bash/bash-0-overview.md

docs/pages/bash/bash-7-commands.md

docs/pages/bash_manip/bash_manip-0-overview.md

docs/pages/bash_manip/bash_manip-1-introduction.md

docs/pages/bash_manip/bash_manip-2-basics.md

docs/pages/bash_manip/bash_manip-3-grep.md

docs/pages/bash_manip/bash_manip-4-awk copy.md

docs/pages/bash_manip/bash_manip-5-sed.md

docs/pages/bash_manip/images/gff.png

docs/pages/bash_script/bash_script-0-overview.md

docs/pages/bash_script/bash_script-1-intro.md

docs/pages/bash_script/images/bash_scripting.png

mkdocs.yml