Merge branch 'cdybenko-data-dictionary-3' into 'master'

Product Planning data definition updates

See merge request gitlab-org/gitlab!68015

config/metrics/counts_28d/20210216181158_epics.yml

 ---
 data_category: Optional
 key_path: usage_activity_by_stage_monthly.plan.epics
-description: 
+description: Count distinct author ids from epics
 product_section: dev
-product_stage: 
+product_stage: plan
 product_group: group::plan
-product_category: 
+product_category: epics
 value_type: number
 status: data_available
 time_frame: 28d
-data_source: 
+data_source: database
 distribution:
-- ce
+- ee
 tier:
-- free
-skip_validation: true
+- premium
 performance_indicator_type:
 - gmau
 - paid_gmau

config/metrics/counts_all/20210216181134_epics.yml

 ---
 data_category: Operational
 key_path: usage_activity_by_stage.plan.epics
-description:
+description: Count distinct author ids from epics
 product_section: dev
-product_stage:
+product_stage: plan
 product_group: group::plan
-product_category:
+product_category: epics
 value_type: number
 status: data_available
 time_frame: all
-data_source:
+data_source: database
 distribution:
-- ce
+- ee
 tier:
-- free
-skip_validation: true
+- premium