Add documentation for pack and publish

Author: Mackiovello

docs/pack-and-publish.md

@@ -0,0 +1,32 @@
+# pack and publish 
+
+The `publish` and `pack` commands interact with the pkg directory that's 
+created when you run `wasm-pack init`. The `pack` command creates a tarball
+from the pkg directory and the `publish` command creates a tarball from the 
+pkg directory __and__ publishes it to the NPM registry. 
+
+Underneath, these commands use `npm pack` and `npm publish`. You can read
+more about these in the NPM documentation:
+
+- [`npm pack`](https://docs.npmjs.com/cli/pack)
+- [`npm publish`](https://docs.npmjs.com/cli/publish)
+
+Both these commands take the path to the pkg directory as the first argument. 
+You can either set the argument directly to the pkg directory or to the parent 
+of the pkg directory:
+
+```
+$ wasm-pack pack myproject/pkg
+| 🎒  packed up your package!
+$ wasm-pack pack myproject
+| 🎒  packed up your package!
+```
+
+If you try to call `pack` or `publish` on another directory, you get an error:
+
+```
+$ wasm-pack pack myproject/src/
+Unable to find the pkg directory at path 'myproject/src/', or in a child directory of 'myproject/src/'
+```
+
+If you don't set a path, they use the current directory as the path.

docs/pack.md

@@ -5,6 +5,8 @@ use slog::Logger;
 use std::result;
 use PBAR;
 
+/// Executes the 'npm pack' command on the 'pkg' directory
+/// which creates a tarball that can be published to the NPM registry
 pub fn pack(path: Option<String>, log: &Logger) -> result::Result<(), Error> {
     let crate_path = set_crate_path(path);
 

docs/publish.md

@@ -5,6 +5,8 @@ use slog::Logger;
 use std::result;
 use PBAR;
 
+/// Creates a tarball from a 'pkg' directory
+/// and publishes it to the NPM registry
 pub fn publish(path: Option<String>, log: &Logger) -> result::Result<(), Error> {
     let crate_path = set_crate_path(path);