Update README steps for install and local development

[jbw976]

Description of your changes

This PR updates a few resources in this provider-helm repository, mainly the README.md, as a result of trying out the steps for installing and local development and fixing/cleaning issues along the way.

The entire README.md now works for me with the latest Crossplane v1.15.1.

I have:

• [x] Read and followed Crossplane's contribution process.
• [x] Run make reviewable to ensure this PR is ready for review.

How has this code been tested

I took an entire pass through the updated README.md - here are a few highlights of the functionality working as expected:

Basic install with no modifications results in a healthy package:

❯ crossplane xpkg install provider xpkg.upbound.io/crossplane-contrib/provider-helm:v0.17.0
provider/crossplane-contrib-provider-helm created

❯ k get pkg
NAME                                                          INSTALLED   HEALTHY   PACKAGE                                                    AGE
provider.pkg.crossplane.io/crossplane-contrib-provider-helm   True        True      xpkg.upbound.io/crossplane-contrib/provider-helm:v0.17.0   13s

Quick start to install provider and in-cluster config, then successfully install wordpress helm chart:

❯ kubectl apply -f ./examples/provider-config/provider-incluster.yaml
provider.pkg.crossplane.io/provider-helm created
deploymentruntimeconfig.pkg.crossplane.io/provider-helm created
clusterrolebinding.rbac.authorization.k8s.io/provider-helm-cluster-admin created

❯ kubectl apply -f ./examples/provider-config/provider-config-incluster.yaml
providerconfig.helm.crossplane.io/helm-provider created

❯ kubectl create -f examples/sample/release.yaml
release.helm.crossplane.io/wordpress-example created

❯ k get releases
NAME                CHART       VERSION   SYNCED   READY   STATE      REVISION   DESCRIPTION        AGE
wordpress-example   wordpress   15.2.5    True     True    deployed   1          Install complete   62s

make run works OK for local development testing:

❯ make run
...
12:32:21 [ .. ] Running Crossplane locally out-of-cluster . . .
customresourcedefinition.apiextensions.k8s.io/providerconfigs.helm.crossplane.io created
customresourcedefinition.apiextensions.k8s.io/providerconfigusages.helm.crossplane.io created
customresourcedefinition.apiextensions.k8s.io/releases.helm.crossplane.io created
go run cmd/provider/main.go -d
...
2024-04-08T12:32:55.448+0200	DEBUG	provider-helm	Creating	{"request": "wordpress-example"}
2024-04-08T12:32:55.826+0200	DEBUG	provider-helm	creating [9] resource(s)
2024-04-08T12:32:55.873+0200	DEBUG	provider-helm	Successfully requested creation of external resource	{"controller": "managed/release.helm.crossplane.io", "request": {"name":"wordpress-example"}, "uid": "3855b525-1bac-448c-848e-47dcb5b9b6b5", "version": "833", "external-name": "", "external-name": "wordpress-example"}
...

❯ k get releases
NAME                CHART       VERSION   SYNCED   READY   STATE      REVISION   DESCRIPTION        AGE
wordpress-example   wordpress   15.2.5    True     True    deployed   1          Install complete   102s