chore(README): add install instruction for package manager

.idea/workspace.xml

@@ -5,7 +5,7 @@
   </component>
   <component name="ChangeListManager">
     <list default="true" id="2f47370d-26d1-4fc6-a93f-363c8b4c6e5a" name="Changes" comment="">
-      <change beforePath="$PROJECT_DIR$/.gitlab-ci.yml" beforeDir="false" afterPath="$PROJECT_DIR$/.gitlab-ci.yml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
     </list>
     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -83,7 +83,7 @@
       <option name="presentableId" value="Default" />
       <updated>1724140762915</updated>
       <workItem from="1724140765116" duration="10726000" />
-      <workItem from="1724224393281" duration="7221000" />
+      <workItem from="1724224393281" duration="7443000" />
     </task>
     <servers />
   </component>

README.md

@@ -14,6 +14,13 @@ $ gpm use al
 Using profile Leo (skole) <alingval@stud.ntnu.no> OK
 ```
 
+## Installation from registry
+```bash
+$ pip install gpm --index-url https://gitlab.stud.idi.ntnu.no/api/v4/projects/28445/packages/pypi/simple
+# or
+$ pipx install gpm --index-url https://gitlab.stud.idi.ntnu.no/api/v4/projects/28445/packages/pypi/simple
+```
+
 ## Build from setup
 ```bash
 $ git clone