chore: define a FROM alias (#26)

while the existing setup works, we're following best practices of aliasing a FROM layer ✅

Co-authored-by: surtur <a_mirre@utb.cz>
Reviewed-on: #26
Co-authored-by: wanderer <wanderer@noreply.git.dotya.ml>
Co-committed-by: wanderer <wanderer@noreply.git.dotya.ml>

Dockerfile

@@ -1,4 +1,4 @@
-FROM immawanderer/fedora-hugo:latest
+FROM immawanderer/fedora-hugo:latest AS hugobuild
 RUN mkdir -pv /homepage
 COPY . /homepage
 
@@ -12,7 +12,7 @@ RUN hugo --minify --gc=true
 WORKDIR /
 
 FROM nginx:mainline-alpine
-COPY --from=0 /homepage/public/ /usr/share/nginx/html
+COPY --from=hugobuild /homepage/public/ /usr/share/nginx/html
 
 # tripple slash reference
 # https://stackoverflow.com/questions/5190966/using-sed-to-insert-tabs/5191165#5191165