Switch to yarn lock and tweak configs so tests are running and change…

… can be made iteratively (#26)

* upgrade actions and tests so that improvements can be made iteratively

* add npm/yarn commands and fix prettier issue in tests

* add markdown checking, fix initial issues

.flowconfig

@@ -1,3 +1,4 @@
 [ignore]
 .*/dist/.*
 .*/__tests__/.*
+.*/node_modules/resolve/test/resolver/malformed_package_json/package.json

.markdownlint.json

@@ -0,0 +1,15 @@
+{
+    "default": true,
+    "MD013": {
+      "line_length": 10000,
+      "headings": false,
+      "code_blocks": false,
+      "tables": false
+    },
+    "MD024": {
+      "siblings_only": true
+    },
+    "MD041": false,
+    "MD033": false,
+    "MD001": false
+  }

README.md

@@ -18,7 +18,7 @@ Data snapshots should be committed to version control, as regular snapshot files
 
 ### Installing
 
-```
+```bash
 npm i --save-dev data-snapshot
 ```
 
@@ -40,14 +40,14 @@ test('some-spec', async () => {
 
 The data is never actually expired (to avoid CI unintentionally triggering an Ajax call, etc). However, if you would like to be reminded with a console warning to update your data periodically, set an expires flag.
 
-```
+```javascript
 const ONE_MONTHISH = 1000 * 60 * 60 * 24 * 30;
 dataSnapshot('key', thunkPromise, {expires: Date.now() + ONE_MONTHISH});
 ```
 
 ## API
 
-```
+```javascript
 dataSnapshot<D>(
   name: string,
   thunkPromise: () => Promise<D>,
@@ -59,7 +59,7 @@ dataSnapshot<D>(
 
 ## Running the tests
 
-```
+```bash
 npm test
 ```