v1 spec: fix typos and formatting

Signed-off-by: Tomas Tomecek <ttomecek@redhat.com>

image/spec/v1.md

@@ -31,7 +31,7 @@ This specification uses the following terms:
         Image JSON
     </dt>
     <dd>
-        Each layer has an associated A JSON structure which describes some
+        Each layer has an associated JSON structure which describes some
         basic information about the image such as date created, author, and the
         ID of its parent image as well as execution/runtime configuration like
         its entry point, default arguments, CPU/memory shares, networking, and
@@ -81,7 +81,7 @@ This specification uses the following terms:
         times of any entries differ. For this reason, image checksums are
         generated using the TarSum algorithm which produces a cryptographic
         hash of file contents and selected headers only. Details of this
-        algorithm are described in the separate [TarSum specification](https://github.com/docker/docker/blob/master/pkg/tarsum/tarsum_spec.md).
+        algorithm are described in the separate <a href="https://github.com/docker/docker/blob/master/pkg/tarsum/tarsum_spec.md">TarSum specification</a>.
     </dd>
     <dt>
         Tag
@@ -492,9 +492,9 @@ Changeset tar archives.
 There is also a format for a single archive which contains complete information
 about an image, including:
 
-    - repository names/tags
-    - all image layer JSON files
-    - all tar archives of each layer filesystem changesets
+ - repository names/tags
+ - all image layer JSON files
+ - all tar archives of each layer filesystem changesets
 
 For example, here's what the full archive of `library/busybox` is (displayed in
 `tree` format):
@@ -523,10 +523,10 @@ For example, here's what the full archive of `library/busybox` is (displayed in
 There are one or more directories named with the ID for each layer in a full
 image. Each of these directories contains 3 files:
 
-    * `VERSION` - The schema version of the `json` file
-    * `json` - The JSON metadata for an image layer
-    * `layer.tar` - The Tar archive of the filesystem changeset for an image
-      layer.
+ * `VERSION` - The schema version of the `json` file
+ * `json` - The JSON metadata for an image layer
+ * `layer.tar` - The Tar archive of the filesystem changeset for an image
+   layer.
 
 The content of the `VERSION` files is simply the semantic version of the JSON
 metadata schema: