added a real readme with a bit of docs

README

@@ -1,17 +1,80 @@
-ergit
+ErlanGit
 ====================
 
-ergit cat-file (commit, tree, blob, tag)
+This is a pure-Erlang implementation of a bunch of Git functionality.  Currently
+it is capable of reading Git objects out of loose or packfile formats and
+parsing tree and commit objects into more meaningful data structures.
 
-ergit log
+Basic API
+====================
+
+First you initialize a Git object with the path to a Git repository:
+
+    Git = git:open("test_git")
+
+You can get the type, size and data for any object in Git with the
+git:object_data call:
+
+  {Type, Size, Data} = git:object_data(Git, "8d47f3435ce5dfd0b2ab5758590c2db21b5294b4")
+
+Type is a term (one of commit, tree, blob, tag), Size is an int of the size of
+the object and Data is a binary of the object data.
+
+You can use object_exists to get a true/false back as to if a given object
+exists in the database.
+
+  Result = git:object_exists(Git, "8d47f3435ce5dfd0b2ab5758590c2db21b5294b4")
+
+You can get a topographically ordered listing of the commit SHAs reachable from
+a given array of commit SHAs with the git:rev_list command
+
+  RevList = git:rev_list(Git, ["25daa907ccb6feb267bfec70a130d5fe13e48a79"])
+
+That command will return an array of commit SHA strings:
+
+  RevList: ["25daa907ccb6feb267bfec70a130d5fe13e48a79",
+            "dd991a4966e8807d448305e67a9b3727efc6060c",
+            "be62addb149d286893e2ec254e0dc783a871e8af",
+            "208fc4a6a08fb1e5136cf9943d79ad81097a0f36",
+            "ef8285c69ceac3f2ff2fee154d3d6ad6a71fb826",
+            "61fa970afbf82f79611220203213cd9562a809e3",
+            "a361a3163a1b521f277e3877232d94b787750c36"]
+
+You can get formatted data back for tree and commit objects (and blobs, but it
+just returns a string of the blob) with the git:object/2 call
+
+    {ok, Commit} = git:object(Git, "25daa907ccb6feb267bfec70a130d5fe13e48a79")
+
+That will return a Commit object who's record looks like this:
+
+  -record(commit, {sha, parents, tree,
+                   author, committer, encoding, message}).
+
+So you can then get the array of parent SHAs with Commit#commit.parents, or
+the commit message with Commit#commit.message.
+
+If you run git:object/2 with a tree SHA, it will give you back an array of tree
+entries, each of which is a tree record:
+
+   -record(tree, {mode, name, sha}).
+
+IO Git API
+===================
+
+There are also a few output functions to help look at the data returned.  You
+can get the equivalent of the 'git log' output with the git_io:print_log command.
+
+   git_io:print_log(Git, ["25daa907ccb6feb267bfec70a130d5fe13e48a79"])
+
+That will print to stdout something like this:
+
+  commit 61fa970afbf82f79611220203213cd9562a809e3
+  Author: Scott Chacon <schacon@gmail.com> 1258278496 +0100
 
-ergit status
-ergit diff
+  added test one
 
-ergit add
-ergit stage
-ergit commit
+  commit a361a3163a1b521f277e3877232d94b787750c36
+  Author: Scott Chacon <schacon@gmail.com> 1258278448 +0100
 
-ergit push
+  first commit
 
-ergit serve