Added instructions on how to install age for postgresql

lightrag/api/docs/LightRagWithPostGRESQL.md

@@ -57,10 +57,9 @@ ALTER USER your_new_role WITH PASSWORD 'your_secure_password';
 \q
 ```
 
-### 3. Install PGVector Extension
-
-Install necessary dependencies and compile the extension:
+### 3. Install PGVector and Age Extensions
 
+Install PGVector:
 ```bash
 sudo apt install postgresql-server-dev-all
 cd /tmp
@@ -69,6 +68,15 @@ cd pgvector
 make
 sudo make install
 ```
+Install age:
+```bash
+sudo apt-get install build-essential libpq-dev
+cd /tmp
+git clone https://github.com/apache/age.git
+cd age
+make
+sudo make install
+```
 
 ### 4. Create a Database for LightRAG