Elaborate on the project’s goals in the README.md

Although the tool itself doesn’t do anything yet, this commit introduces the README.md file to serve as an informative welcome to contributors and readers of the project’s source code’s history.

Once the project works as described, the README.md will serve as the home page for the generated website.

README.md

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..7762285
--- /dev/null
+++ b/README.md
@@ -0,0 +1,44 @@
+git-read
+===
+
+Generate a website based on a project's Git history.
+
+* Serve the project's `README.md` as the homepage
+* Index the history through its commits
+* Transforms commit messages HTML through a syntax-aware Markdown parser
+* Display the commits alongside their code changes
+
+Command-line Interface
+---
+
+Once installed, make sure that the `bin/git-read` executable is available on
+your path so that the [`git` program can invoke it as a subcommand][subcommand].
+
+To learn of the ways to to invoke the command, execute `git read --help`:
+
+```
+usage: git read [--help] [-v|--verbose] [-s|--server|--serve]
+                [-g | --git-dir <path>] [-o | --output-dir <path>]
+
+Generate HTML from your project's Git history
+
+OPTIONS
+
+      --output-dir
+          specify the directory where the site will be built
+
+      --git-dir
+          specify the parent directory of the project's .git/ directory
+
+      --verbose
+          print debugging information during the build process
+
+      --server
+          build and serve assets with a server available at
+          http://127.0.0.1:4567
+
+      --help
+          generate this help output
+```
+
+[subcommand]: http://mirrors.edge.kernel.org/pub/software/scm/git/docs/howto/new-command.html