Fix the baseURL for dev and prod use caes

The baseURL is not set for dev and prod which causes the following
issues:
- for dev, the URL shown on the console is not the correct one
- for prod, the generated sitemap.xml uses relative URLs, which
  makes it not parsable by the search engine

This is already setup correctly for deploy-previews.
Signed-off-by: NAndrea Frittoli <andrea.frittoli@gmail.com>

Makefile

@@ -5,6 +5,7 @@ sync:
 .PHONY: serve
 serve:
 	hugo server \
+	--baseURL $(URL) \
 	--buildDrafts \
 	--buildFuture \
 	--disableFastRender \
@@ -13,7 +14,7 @@ serve:
 
 .PHONY: production-build
 production-build: sync
-	hugo
+	hugo --baseURL $(URL)
 
 .PHONY: preview-build
 preview-build: sync

netlify.toml

 [build]
-publish = "public"
-command = "make production-build"
+  publish = "public"
+  command = "make production-build"
 
 [build.environment]
-HUGO_VERSION = "0.53"
+  HUGO_VERSION = "0.53"
+
+[dev]
+  command = "make serve URL=http://localhost:8888/"
 
 [context.deploy-preview]
-command = "make preview-build"
+  command = "make preview-build"
 
 [context.branch-deploy]
-command = "make preview-build"
+  command = "make preview-build"