Add PROCESSES document (vmware-tanzu#44)

* Add CODEOWNERS

I used this syntax in CODEOWNERS:

```
/chart/<name-of-chart> @maintainer
```

It matches any files in the chart directory at the root of the repository and any of its  subdirectories.
Without the leading `/` it would also match directories found somewhere
else. It's unlikely that those names would be used, but it does not harm
to do it this way.

Part-of: vmware-tanzu#38

Signed-off-by: Torsten Walter <mail@torstenwalter.de>

* sort charts alphabetically

Signed-off-by: Torsten Walter <mail@torstenwalter.de>

* adjust existing CODEOWNERS

Signed-off-by: Torsten Walter <mail@torstenwalter.de>

* link to CODEOWNERS file and fixed spelling

Signed-off-by: Torsten Walter <mail@torstenwalter.de>

.github/CODEOWNERS

@@ -1,20 +1,25 @@
 # See https://github.com/scottrigby/prometheus-helm-charts/issues/12
 # https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners
+# https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners#codeowners-syntax
 
-charts/prometheus/ @gianrubio @zanhsieh @Xtigyro
-charts/prometheus-adapter/ @mattiasgees @steven-sheehy @hectorj2f
-charts/prometheus-blackbox-exporter/ @desaintmartin @gianrubio
-charts/prometheus-cloudwatch-exporter/ @gianrubio @torstenwalter @asherf
-charts/prometheus-consul-exporter @timm088
-charts/prometheus-couchdb-exporter @gkarthiks
-charts/prometheus-mongodb-exporter @steven-sheehy
-charts/prometheus-mysql-exporter @juanchimienti @monotek
-charts/prometheus-nats-exporter @okgolove @caarlos0
-charts/prometheus-node-exporter @gianrubio @vsliouniaev
-charts/prometheus-operator @vsliouniaev @bismarck @gianrubio
-charts/prometheus-postgres-exporter @gianrubio
-charts/prometheus-pushgateway @gianrubio @cstaud
-charts/prometheus-rabbitmq-exporter @juanchimienti
-charts/prometheus-redis-exporter @acondrat
-charts/prometheus-snmp-exporter @miouge1
-charts/prometheus-to-sd @acondrat
+# The repo admins team will be the default owners for everything in the repo.
+# Unless a later match takes precedence, they will be requested for review when someone opens a pull request.
+* @prometheus-community/helm-charts-admins
+
+/charts/prometheus/ @gianrubio @zanhsieh @Xtigyro
+/charts/prometheus-adapter/ @mattiasgees @steven-sheehy @hectorj2f
+/charts/prometheus-blackbox-exporter/ @desaintmartin @gianrubio
+/charts/prometheus-cloudwatch-exporter/ @gianrubio @torstenwalter @asherf
+/charts/prometheus-consul-exporter @timm088
+/charts/prometheus-couchdb-exporter @gkarthiks
+/charts/prometheus-mongodb-exporter @steven-sheehy
+/charts/prometheus-mysql-exporter @juanchimienti @monotek
+/charts/prometheus-nats-exporter @okgolove @caarlos0
+/charts/prometheus-node-exporter @gianrubio @vsliouniaev
+/charts/prometheus-operator @vsliouniaev @bismarck @gianrubio
+/charts/prometheus-postgres-exporter @gianrubio
+/charts/prometheus-pushgateway @gianrubio @cstaud
+/charts/prometheus-rabbitmq-exporter @juanchimienti
+/charts/prometheus-redis-exporter @acondrat @zanhsieh
+/charts/prometheus-snmp-exporter @miouge1
+/charts/prometheus-to-sd @acondrat

PROCESSES.md

@@ -0,0 +1,11 @@
+# Processes
+
+This document outlines processes and procedures for some common tasks in the charts repository.
+
+## Adding chart maintainers
+
+Chart maintainers are defined within the chart itself.
+So the procedure for adding maintainers is to add them there.
+The pull request which does that should also update [CODEOWNERS](./github/CODEOWNERS) file to that the new maintainer is able to approve pull requests.
+One of the existing chart maintainers needs to approve the PR in addition one of the repository admins needs to approve it.
+They are then responsible for also granting the new maintainer write permissions to this repository.