add definition of static vs dynamic

Signed-off-by: Thomas Poignant <[email protected]>

website/src/pages/specification/20241027-flagsets.md

@@ -18,6 +18,9 @@ Description: Flag sets are a way to group flags together.
 > _Source: [Openfeature glossary](https://openfeature.dev/specification/glossary/#flag-set)._
 
 
+- **static flag set**: the flag set is defined in the retriever configuration, we know in advance that this flag set exists.
+- **dynamic flag set**: the flag set is defined in the flag configuration file, we don't know in advance which flag sets exist.
+
 ## Context
 
 As of today, GO Feature Flag is evaluating flag differently for client and server evaluations.
@@ -117,6 +120,8 @@ authorizedKeys:
 - The flag set configuration is at the same place as the flag configuration, so it is possible to edit the flag set name directly inside the file _(risk of overriding another flag set)_.
 - If we want the same flag to be part of multiple flag sets, we need to duplicate the flag in multiple files.
 
+---
+
 ### Solution 2: specify the flag set in the retriever configuration
 
 In this solution we consider that we need at least one file per flag set.  
@@ -171,6 +176,8 @@ authorizedKeys:
 **CON**
 - If we want the same flag to be part of multiple flag sets, we need to duplicate the flag in multiple files.
 
+---
+
 ### Solution 3
 In this solution we want to offer multiple way to specify the flag set in the configuration.  
 This solution will be more complex to implement, but it will give more flexibility to the users.