add instructions how to update themes

README.md

@@ -2,4 +2,21 @@
 
 homepage
 
+* [Hugo Quick start](https://gohugo.io/getting-started/quick-start/)
+* Preview: `hugo server -D`
+
+## Theme
+
+### Add
+```bash
+git submodule add https://github.com/theNewDynamic/gohugo-theme-ananke.git themes/ananke
+echo "theme = 'ananke'" >> hugo.toml
+```
+### Update
+```bash
+git submodule update --remote
+git add themes/.
+git commit -m "theme submodule updated"
+```
+
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