Add setup-pollapo docs (#2)

Author: hyp3rflow

docs/getting-started/setup-pollapo.md

@@ -0,0 +1,35 @@
+## Login first
+
+After installing the `pollapo` cli, you have to login to the Github using `pollapo`.  
+`pollapo` installs your protobuf packages from Github repository.
+
+```bash
+pollapo login
+```
+
+## Install protobuf dependency
+
+For add dependency, you have to just `pollapo add <package-name>@<version|branch|commit>` and say yes to the `pollapo` cli to create new `pollapo.yml` file. Here is an example:
+```bash
+pollapo add pbkit/interface-pingpong-server@main
+```
+
+Now you can see the `pollapo.yml` file in your project root.
+
+```yaml
+deps:
+  - pbkit/interface-pingpong-server@main
+root:
+  lock:
+    pbkit/interface-pingpong-server@main: 58425678c6284305dd09130075cecb54a3a3d32c
+```
+The dependency infos and the lock hash of the packages will be printed in `pollapo.yml`.
+(The hash can be different!) This will resolve the version issue of the packages when you re-install deps with branch name.
+
+## Installed protobuf packages
+
+Use `pollapo install` to re-install your all deps. You can find installed protobuf packages in `.pollapo` directory.
+
+If you want to update your lock version of dependency, just remove the lock line and re-install with `pollapo install`.
+
+Perfect! Now you can use `pb` cli to compile the protobuf schema.