Docs: Incorporate parameter categories into the config reference (#1128)

docs/sources/configuration/reference-configuration-parameters.md

@@ -36,6 +36,32 @@ brackets indicate that a parameter is optional.
   - `2006-01-20T15:04` (local timezone)
   - RFC 3339 formats: `2006-01-20T15:04:05Z` (UTC) or `2006-01-20T15:04:05+07:00` (explicit timezone)
 
+## Parameter categories
+
+In order to simplify Mimir configuration, we categorize parameters by
+maturity level and intended use:
+
+- **Basic** parameters are ones that we expect the majority of users to modify.
+  Examples of basic parameters are object store credentials and
+  other dependency connection information.
+  These parameters will generally remain stable for long periods of time,
+  and they focus on user goals.
+  In this reference, any parameters that are not marked as `(advanced)` or
+  `(experimental)` are in the basic category.
+
+- **Advanced** parameters are ones that few users will change
+  from their default values.
+  There are strong use cases for altered values.
+  In this reference, advanced-category parameters include `(advanced)` at
+  the beginning of their description.
+
+- **Experimental** parameters are for new and experimental features.
+  These parameters permit
+  early adopters and Mimir developers to gain confidence with new
+  features.
+  In this reference, experimental-category parameters include `(experimental)` at
+  the beginning of their description.
+
 ## Use environment variables in the configuration
 
 You can use environment variable references in the YAML configuration file

docs/sources/configuration/reference-configuration-parameters.template

@@ -36,6 +36,32 @@ brackets indicate that a parameter is optional.
     - `2006-01-20T15:04` (local timezone) 
     - RFC 3339 formats: `2006-01-20T15:04:05Z` (UTC) or `2006-01-20T15:04:05+07:00` (explicit timezone)
 
+## Parameter categories
+
+In order to simplify Mimir configuration, we categorize parameters by
+maturity level and intended use:
+
+- **Basic** parameters are ones that we expect the majority of users to modify.
+Examples of basic parameters are object store credentials and
+other dependency connection information.
+These parameters will generally remain stable for long periods of time,
+and they focus on user goals.
+In this reference, any parameters that are not marked as `(advanced)` or
+`(experimental)` are in the basic category.
+
+- **Advanced** parameters are ones that few users will change
+from their default values. 
+There are strong use cases for altered values.
+In this reference, advanced-category parameters include `(advanced)` at
+the beginning of their description.
+
+- **Experimental** parameters are for new and experimental features.
+These parameters permit
+early adopters and Mimir developers to gain confidence with new
+features.
+In this reference, experimental-category parameters include `(experimental)` at
+the beginning of their description.
+
 ## Use environment variables in the configuration
 
 You can use environment variable references in the YAML configuration file