docs: readme

Signed-off-by: Carlos Alexandro Becker <[email protected]>

README.md

@@ -1,7 +1,19 @@
 # fileglob
 
+A file globbling library.
+
 ## What
 
+`fileglob` is a glob library that uses [gobwas/glob](https://github.com/gobwas/glob) underneath
+and returns only matching files.
+
 ## Why
 
-## vs Other libraries
+[gobwas/glob](https://github.com/gobwas/glob) is very well implemented: it has
+a lexer, compiler, and all that, which seems like a better approach than most
+libraries do: regex.
+
+It doesn't have a `Walk` method though, and we needed it
+[in a couple of places](https://github.com/goreleaser/nfpm/issues/232).
+So we decided to implement it ourselves, a little bit based on how
+[mattn/go-zglob](https://github.com/mattn/go-zglob) works.