fix: README.md

Author: vasil-cf

codefresh/README.md.gotmpl

@@ -837,6 +837,11 @@ Ref:
 - [Create an Index in Atlas DB](https://www.mongodb.com/docs/atlas/atlas-ui/indexes/#create-an-index)
 - [Create an Index with mongosh](https://www.mongodb.com/docs/manual/reference/method/db.collection.createIndex/)
 
+##### ⚠️ Upgrading when the indexes are maintained manually
+
+If you maintain indexes manually and you upgrade your On-Prem installation you must create all indexes which were introduced from your current version up to the version you upgrade to manually.
+
+You can follow [Upgrading section](#upgrading) to see what changes were made for indexes in every specific release.
 
 ### High Availability
 
@@ -1751,7 +1756,7 @@ nomios:
     ...
 ```
 
-### To 2.0.12
+### To 2-0-12
 
 #### ⚠️ Legacy ChartMuseum subchart deprecation
 
@@ -2038,6 +2043,12 @@ cfapi:
 
 [Auto-index creation in MongoDB](#auto-index-creation-in-mongodb)
 
+#### ⚠️ New indexes in MongoDB
+
+If you maintain indexes manually (i.e. [Auto-index creation](#enabling-auto-index-creation) is off) you must create the following index **before** the upgrade:
+
+- [Database: `read-models`, collection: `images-binaries`, index: `accountId_1_imageName_1`](https://github.com/codefresh-io/codefresh-onprem-helm/tree/release-2.8/indexes/read-models/images-binaries.json#L75-L94)
+
 ### To 2-7-0
 
 ### [What's new in 2.7.x](https://codefresh.io/docs/docs/whats-new/on-prem-release-notes/#on-premises-version-27)
@@ -2069,6 +2080,15 @@ global:
                   - "value"
 ```
 
+#### ⚠️ New indexes in MongoDB
+
+If you maintain indexes manually (i.e. [Auto-index creation](#enabling-auto-index-creation) is off) you must create the following indexes **before or right after** the upgrade:
+
+> ⚠ **Note!** In case if you create indexes **before** the upgrade, please, create `codefresh.feature-store-versioned` collection manually in advance.
+
+- [Database: `codefresh`, collection: `feature-store-versioned`, index: `createdAt_1`](https://github.com/codefresh-io/codefresh-onprem-helm/tree/release-2.8/indexes/codefresh/feature-store-versioned.json#L2-L9)
+- [Database: `codefresh`, collection: `feature-store-versioned`, index: `LDRedisStoreVersion_1__id_-1`](https://github.com/codefresh-io/codefresh-onprem-helm/tree/release-2.8/indexes/codefresh/feature-store-versioned.json#L10-L17)
+
 ### To 2-8-0
 
 ### [What's new in 2.8.x](https://codefresh.io/docs/docs/whats-new/on-prem-release-notes/#on-premises-version-28)