Using local package in shell manifest

[Jesse]

Hello,

I have written a package that I have installed with "guix package 
--install-from-file=crosstool-ng.scm". I was able to get it to build and 
install. I can use it if I do "source ~/.guix-profile/etc/profile".

However, I would like to add it to a shell manifest. My manifest just 
includes

(specifications->manifest
  (list "gcc" "git" "zsh" "crosstool-ng"))

My understanding is that "specifications->manifest" is supposed to 
search for the packages in the list? It returns the following when I 
rung "guix shell" in the directory with the manifest.scm:

guix shell: loading environment from 
'/home/jesse/Code/guix-tests/manifest.scm'...
hint: Consider passing the `--check' option once to make sure your shell 
does not
clobber environment variables.

guix shell: error: crosstool-ng: unknown package
guix shell: error: failed to load 
'/home/jesse/Code/guix-tests/manifest.scm':
gnu/packages.scm:545:4: In procedure specification->package+output:
Throw to key `quit' with args `(1)'.

I'd imagine it doesn't know where to look for the package? Is there a 
way to tell guix shell where to look? If not, is there a way to include 
the package in the manifest file? For what it's worth, I have attached 
the package file in question.

This is also my first foray into Guix and Guile, so I've been kind of 
banging my head through writing a package and the manual but I got a 
little stuck here.

Thanks

crosstool-ng.scm
Description: Text Data