docs fix serve-docs directive in makefile (#756)

Signed-off-by: emirot <[email protected]>

Author: emirot

Makefile

@@ -304,7 +304,7 @@ $(GORELEASER): $(LOCALBIN)
 
 .PHONY: serve-docs
 serve-docs:
-	$(CONTAINER_TOOL) run ${MKDOCS_RUN_ARGS} --rm -it -p 8000:8000 -v ${CURRENT_DIR}:/docs -w /docs --entrypoint "" ${MKDOCS_DOCKER_IMAGE} sh -c 'pip install mkdocs; pip install $$(mkdocs get-deps); mkdocs serve -a $$(ip route get 1 | awk '\''{print $$7}'\''):8000'
+	$(CONTAINER_TOOL) run ${MKDOCS_RUN_ARGS} --rm -it -p 8000:8000 -v ${CURRENT_DIR}:/docs -w /docs --entrypoint "" ${MKDOCS_DOCKER_IMAGE} sh -c 'pip install -r docs/requirements.txt; mkdocs serve -a $$(ip route get 1 | awk '\''{print $$7}'\''):8000'
 
 .PHONY: lint-docs
 lint-docs:  ## Build docs and fail if there are warnings