add git URL format to json + developers docs

doc/cli/developers.md

@@ -27,12 +27,23 @@ A package is:
 * d) a `<name>@<version>` that is published on the registry with (c)
 * e) a `<name>@<tag>` that points to (d)
 * f) a `<name>` that has a "latest" tag satisfying (e)
+* g) a `git` url that, when cloned, results in (a).
 
 Even if you never publish your package, you can still get a lot of
 benefits of using npm if you just want to write a node program (a), and
 perhaps if you also want to be able to easily install it elsewhere
 after packing it up into a tarball (b).
 
+Git urls can be of the form:
+
+    git://github.com/user/project.git#commit-ish
+    git+ssh://user@hostname:project.git#commit-ish
+    git+http://user@hostname/project/blah.git#commit-ish
+    git+https://user@hostname/project/blah.git#commit-ish
+
+The `commit-ish` can be any tag, sha, or branch which can be supplied as
+an argument to `git checkout`.  The default is `master`.
+
 ## The package.json File
 
 You need to have a `package.json` file in the root of your project to do

doc/cli/json.md

@@ -332,6 +332,7 @@ is a semver compatible version identifier.
 * `""` (just an empty string) Same as `*`
 * `version1 - version2` Same as `>=version1 <=version2`.
 * `range1 || range2` Passes if either range1 or range2 are satisfied.
+* `git...` See 'Git URLs as Dependencies' below
 
 For example, these are all valid:
 
@@ -387,6 +388,18 @@ of a version range.
 This tarball will be downloaded and installed locally to your package at
 install time.
 
+### Git URLs as Dependencies
+
+Git urls can be of the form:
+
+    git://github.com/user/project.git#commit-ish
+    git+ssh://user@hostname:project.git#commit-ish
+    git+http://user@hostname/project/blah.git#commit-ish
+    git+https://user@hostname/project/blah.git#commit-ish
+
+The `commit-ish` can be any tag, sha, or branch which can be supplied as
+an argument to `git checkout`.  The default is `master`.
+
 ## devDependencies
 
 If someone is planning on downloading and using your module in their