Avoid HTML img tag

[rgaiacs]

Will be nice to avoid HTML img tag. For example, instead of

<img src="fig/foo.svg" alt="Foo" />

we can use

![Foo](fig/foo.svg)

The list of img elements to replace is

$ grep img *.md      
01-filedir.md:<img src="fig/filesystem.svg" alt="The Filesystem" />
01-filedir.md:<img src="fig/home-directories.svg" alt="Home Directories" />
01-filedir.md:<img src="fig/homedir.svg" alt="Nelle's Home Directory" />
01-filedir.md:<img src="fig/filesystem-challenge.svg" alt="Filesystem for Challenge Questions" />
02-create.md:<img src="fig/nano-screenshot.png" alt="Nano in Action" />
06-find.md:<img src="fig/find-file-tree.svg" alt="File Tree for Find Example" />

[gvwilson]

+1.