Require @changesets/cli resolving from cwd (#67)

* Resolve @changesets/cli with resolve-from

* Use require.resolve directly

* Add documentation section to README

* Add custom version command docs for Yarn 2

src/run.ts

@@ -181,17 +181,20 @@ export async function runVersion({
     let [versionCommand, ...versionArgs] = script.split(/\s+/);
     await exec(versionCommand, versionArgs, { cwd });
   } else {
-    let changesetsCliPkgJson = await require(path.join(
-      cwd,
-      "node_modules",
-      "@changesets",
-      "cli",
-      "package.json"
+    let changesetsCliPkgJson = await require(require.resolve(
+      "@changesets/cli/package.json",
+      { paths: [cwd] }
     ));
     let cmd = semver.lt(changesetsCliPkgJson.version, "2.0.0")
       ? "bump"
       : "version";
-    await exec("node", ["./node_modules/@changesets/cli/bin.js", cmd], { cwd });
+    await exec(
+      "node",
+      [require.resolve("@changesets/cli/bin.js", { paths: [cwd] }), cmd],
+      {
+        cwd,
+      }
+    );
   }
 
   let searchQuery = `repo:${repo}+state:open+head:${versionBranch}+base:${branch}`;