add mongodb section to README

Author: andrii29

README.md

@@ -46,3 +46,45 @@ Ollama allows you to run open-source large language models and keep privacy. Set
 curl -fsSL https://ollama.com/install.sh | sh
 ollama run llama3
 ```
+
+### MongoDB Authentication
+To set up authentication, follow these steps:
+```
+mongosh
+
+use admin
+db.createUser({
+  user: "mongodb-index-advisor",
+  pwd: passwordPrompt(),
+  roles: [ { role: "clusterMonitor", db: "admin" } ]
+})
+
+docker run --rm -it --net host andriik/mongodb-index-advisor -aiProvider ollama -dbName rto -mongoURI "mongodb://mongodb-profiler-exporter:<password>@127.0.0.1:27017/admin?authSource=admin&readPreference=primaryPreferred"
+```
+
+### Enable MongoDB Profiler
+There are two ways to enable profiler in mongodb:
+#### Per Dababase
+```
+use db_name
+db.getProfilingStatus()
+db.setProfilingLevel(1, { slowms: 100 })
+```
+
+#### Globally in mongod.conf
+```yaml
+operationProfiling:
+  mode: slowOp
+  slowOpThresholdMs: 50
+```
+
+### Increase system.profile size
+The default size of the `system.profile` collection is set to 1MB, which can be insufficient for certain scenarios. To address this limitation, you can adjust the size of the collection by recreating it. Note that this process should not be replicated to replicas.
+
+Below are example commands that can be used to increase the size of the system.profile collection:
+```js
+db.setProfilingLevel(0) // Disable profiling temporarily
+db.system.profile.drop() // Drop the existing system.profile collection
+db.createCollection( "system.profile", { capped: true, size: 1024 * 1024 * 50 } ) // 50Mb
+db.setProfilingLevel(1, { slowms: 100 })  // Enable profiling again
+```