Fix typo on guidelines page (#56)

Author: particleflux

guidelines/index.md

@@ -12,7 +12,7 @@ Here we lay down some info on the structure of a package.
 ## bpkg.json
 
 Every package must have a file called `bpkg.json`; it specifies package metadata on the [JSON format][json].
-(For legacy reasons, this file may also be called `pacakge.json`).
+(For legacy reasons, this file may also be called `package.json`).
 
 Here's an example of a well-formed `bpkg.json`: