docs(readme): add image explain to readme

README.md

@@ -98,7 +98,7 @@ docker run gnes/gnes:alpine-latest
 
 This command downloads the latest GNES image (based on [Alpine Linux](https://alpinelinux.org/)) and runs it in a container. When the container runs, it prints an informational message and exits.
 
-#### Choose the right GNES image
+#### 💡 Choose the right GNES image
 
 Besides the `alpine` image optimized for the space, we also provide Buster (Debian 10.0) and Ubuntu 18.04-based images. The table below summarizes [all available GNES tags](https://cloud.docker.com/u/gnes/repository/docker/gnes/gnes). One can fill in `{ver}` with `latest`, `stable` or `v0..xx`. `latest` refers to the **latest master** of this repository, which [may not be stable](./CONTRIBUTING.md#Merging-Process). We recommend you to use an official release by changing the `latest` to a version number, say `v0.0.24`, or simply using `stable` for the last release, e.g. `gnes:ubuntu-stable`
 
@@ -111,12 +111,12 @@ Besides the `alpine` image optimized for the space, we also provide Buster (Debi
   <tr>
     <td><code>alpine-{ver}</code></td>
     <td><img src="https://images.microbadger.com/badges/image/gnes/gnes:alpine-latest.svg"></td>
-    <td>based on Alpine Linux;<br>no deep learning libraries;<br>Extremely lightweight and portable, enables fast scaling on even edge devices.</td>
+    <td>based on Alpine Linux;<br>no deep learning libraries;<br>extremely lightweight and portable, enables fast scaling on even edge devices.</td>
   </tr>
   <tr>
     <td><code>buster-{ver}</code></td>
     <td><img src="https://images.microbadger.com/badges/image/gnes/gnes:buster-latest.svg"></td>
-    <td>based on Debian 10.0;<br>no deep learning libraries;<br>Recommended for building or extending a GNES-Hub image.</td>
+    <td>based on Debian 10.0;<br>no deep learning libraries;<br>recommended for building or extending a GNES-Hub image.</td>
   </tr>
   <tr>
     <td><code>ubuntu-{ver}</code></td>
@@ -126,7 +126,7 @@ Besides the `alpine` image optimized for the space, we also provide Buster (Debi
   <tr>
     <td><code>full-{ver}</code></td>
     <td><img src="https://images.microbadger.com/badges/image/gnes/gnes:full-latest.svg"></td>
-    <td>based on Ubuntu 16.04;<br>python-3.6.8, cuda-10.0, tf1.14, pytorch1.1, faiss, multiple pretrained models; <br>Heavy but self-contained, useful in testing GNES end-to-endly.</td>
+    <td>based on Ubuntu 16.04;<br>python-3.6.8, cuda-10.0, tf1.14, pytorch1.1, faiss, multiple pretrained models; <br>heavy but self-contained, useful in testing GNES end-to-endly.</td>
   </tr>
 </table>