docs(ci): update docs related to changelog (#1180)

chore(ci): update docs related to changelog

Signed-off-by: Maksim Fedotov <maksim.fedotov@flant.com>

Author: nevermarine

.github/PULL_REQUEST_TEMPLATE.md

@@ -27,47 +27,26 @@
 
 ## Changelog entries
 <!---
-  Add one or more changelog entries to present your changes to end users.
-
-  Changelog entry fields description:
-  - `section` - a project scope in the kebab-case (See CONTRIBUTING.md#scope for the list).
-  - `type` - one of the following: fix, feature, chore
-  - `summary` - a ONE-LINE description on how change affects users.
-  - `impact_level` - Optional field: set to 'low' to exclude entry from changelog.
-  - `impact` - Optional field: multiline message on what user should know in the first place, i.e. restarts, breaking changes, deprecated fields, etc. Requires `impact_level: high`.
-
   /!\ See CONTRIBUTING.md for more details. /!\
-
-  Example 1. Significant message at the beginning of the changelog:
-
-section: disks
-type: feat
-summary: "Disks serials are based on uid now."
-impact_level: high
-impact: |
-  Disk serial is now uid-based.
-
-  Using /dev/disk/by-serial/ is not supported anymore.
-
-
-  Example 2. Chore change (not in the Changelog):
-
-section: ci
-type: chore
-summary: "Update checkout and github-script action versions."
-impact_level: low
-
-
-  Example 3. Regular entry in the Changelog:
-
-section: vm
-type: feature
-summary: "virtualMachineClassName field is now required."
-
+  Examples:
+  ```changes
+  section: core
+  type: feature
+  summary: "Node restarts can be avoided by pinning a checksum to a node group in config values."
+  ---
+  section: core
+  type: fix
+  summary: "Nodes with outdated manifests are no longer provisioned on *InstanceClass update."
+  impact_level: high
+  impact: |
+    Expect nodes of "Cloud" type to restart.
+  ---
+  impact_level: low
+  ```
 -->
 
 ```changes
-section: 
-type: 
-summary: 
+section:
+type:
+summary:
 ```

CONTRIBUTING.md

@@ -121,12 +121,12 @@ Supported scopes are the following:
 
   # Maintaining, improving code quality and development workflow.
   - ci
-  
+
   # Maintaining, improving documentation.
   - docs
 
   # Network related changes important for end-user.
-  - network  
+  - network
   ```
 
 #### Subject
@@ -185,12 +185,13 @@ impact: |
     - `feature`: Adds new functionality.
     - `fix`: Resolves user-facing issues.
     - `chore`: Maintenance tasks without direct user impact.
+    - `docs`: Changes to documentation.
 
   - **summary**: (Required) A concise explanation of the change, ending with a period.
 
   - **impact_level**: (Optional) Indicates the significance of the change.
     - `high`: Requires an **impact** description and will be included in "Know before update" sections.
-    - `low`: Minor changes, typically omitted from user-facing changelogs.
+    - `low`: Minor changes, omitted from user-facing changelogs. If this level is specified, all other fields are not validated by GitHub workflow.
 
   - **impact**: (Required if `impact_level` is high) Describes the change's effects, such as expected restarts or downtime.
     - Examples:
@@ -215,9 +216,6 @@ impact: |
   Node checksum calculation is fixed, as well as a race condition during
   the machines (MCM) rendering which caused outdated nodes to spawn.
 ---
-section: ci
-type: fix
-summary: "Improved comments tracking workflow progress."
 impact_level: low
 ```