Fix some outdated information in dev guide

DEVELOPER_GUIDE.md

@@ -2,34 +2,33 @@
 
 This document describes how to set up a development environment for Calico, as well as how to build and test development code.
 
-This guide is broken into the following main sections:
-
-- [Building Calico from scratch](#building-calico-from-scratch)
-- [Deploying your code on Kubernetes](#deploying-your-code-on-kubernetes)
-- [Running automated tests](#running-automated-tests)
-
 Additional developer docs can be found in [hack/docs](hack/docs).
 
 ## Prerequisites:
 
-These build instructions assume you have a Linux build environment
-with:
+These build instructions assume you have a Linux build environment with:
 
 -  Docker
 -  git
 -  make
 
-## Building Calico 
+## Building Calico
 
 ### Building all of Calico
 
 To build all of Calico, run the following command from the root of the repository.
 
 ```
-make image DEV_REGISTRY=my-registry
+make image
 ```
 
-This will produce several container images, each tagged with the registry provided.
+This will produce several container images and may take some time, so you likely want to build the specific image / images that you are working on instead.
+
+The build uses the go package cache and local vendor caching to increase build speed. To perform a clean build, use the `clean` target.
+
+```
+make clean image
+```
 
 ### Build a specific image
 
@@ -50,17 +49,10 @@ build for arm64, run the following:
 make image ARCH=arm64
 ```
 
-- Now, build the YAML manifests that are used to install calico:
+### Updating Calico helm chart and manifests
 
-```
-make dev-manifests
-```
-
-The build uses the go package cache and local vendor caching to increase build speed. To perform a clean build, use the `dev-clean` target.
-
-```
-make dev-clean dev-image
-```
+The Calico helm charts can be found in the `charts/` directory. After making changes to the templates in the chart,
+make sure to run `make gen-manifests` to update the `manifests/` directory, which is largely auto-generated based on the helm chart.
 
 ### Makefile target reference