om2: add data model diagram

Signed-off-by: bwplotka <bwplotka@gmail.com>

Author: bwplotka

.mdox.validator.yaml

@@ -1,6 +1,13 @@
 version: 1
 
-# Don't check external URLs, they can time-out a lot (rate limits).
+explicitLocalValidators: true
 validators:
+  # Don't check external URLs for now, they can time-out a lot (rate limits), so they require extra cache setup.
   - type: ignore
-    regex: http(s|)://.*
+    regex: http(s|)://.*
+  # In docs assets are referenced in links as /assets/..., but the true path is ./public/assets/...
+  - type: local
+    regex: "/assets/.*"
+    anchor: "/public"
+  - type: local
+    regex: ".*"

Makefile

@@ -3,7 +3,7 @@ MD_FILES_TO_FORMAT=docs/specs/om/open_metrics_spec_2_0.md
 
 MDOX="mdox"
 $(MDOX):
-	@go install github.com/bwplotka/mdox@v0.9.0
+	@go install github.com/bwplotka/mdox@d22b1d641c9b4b7a54c95d279231abe6e5e892fd
 
 .PHONY: help
 help: ## Displays help.
@@ -13,7 +13,7 @@ help: ## Displays help.
 fmt: ## Format docs.
 fmt: $(MDOX)
 	@echo "Formatting markdown files..."
-	@$(MDOX) fmt --links.validate $(MD_FILES_TO_FORMAT)
+	@$(MDOX) fmt --links.validate --links.validate.config-file=./.mdox.validator.yaml $(MD_FILES_TO_FORMAT)
 
 .PHONY: check
 check: ## Checks if doc is formatter and links are correct (don't check external links).

docs/specs/om/open_metrics_spec_2_0.md

@@ -68,6 +68,12 @@ Common examples of metric time series would be network interface counters, devic
 
 This section MUST be read together with the ABNF section. In case of disagreements between the two, the ABNF's restrictions MUST take precedence. This reduces repetition as the text wire format MUST be supported.
 
+<!---
+# Diagram source: https://docs.google.com/presentation/d/1ovDkQVm84zo5ktWZVm5XosLS2YMRgdSJCevVivAlLW0/edit?slide=id.g3cfc897512e_0_291#slide=id.g3cfc897512e_0_291
+-->
+
+![om2_datamodel.png](/assets/docs/om2_datamodel.png)
+
 ### Data Types
 
 #### Values