docs(helmv3): rewrite (#19050)

lib/modules/manager/helmv3/readme.md

-Renovate supports updating Helm Chart references within `requirements.yaml` (Helm v2) and `Chart.yaml` (Helm v3) files.
+Renovate supports updating Helm Chart references in:
+
+- `requirements.yaml` files, for Helm v2
+- `Chart.yaml` files, for Helm v3
 
 The `helmv3` manager defines this default registryAlias:
 
@@ -10,13 +13,14 @@ The `helmv3` manager defines this default registryAlias:
 }
 ```
 
-If your Helm charts make use of repository aliases then you will need to configure an `registryAliases` object in your config to tell Renovate where to look for them. Be aware that alias values must be properly formatted URIs.
+If you use repository aliases in your Helm charts then you must set an `registryAliases` object in your configuration file so Renovate knows where to find the repository.
+Alias values must be properly formatted URIs.
 
-If you need to change the versioning format, read the [versioning](https://docs.renovatebot.com/modules/versioning/) documentation to learn more.
+If you need to change the versioning format, read our [versioning](https://docs.renovatebot.com/modules/versioning/) documentation to learn more.
 
 ### Private repositories and registries
 
-To use private sources of Helm charts, you must set the password and username you use to authenticate to the private source.
+To use private sources in your Helm charts, you must set the `password` and `username` you use to authenticate to the private source.
 For this you use a custom `hostRules` array.
 
 #### OCI registries
@@ -25,14 +29,14 @@ For this you use a custom `hostRules` array.
 {
   hostRules: [
     {
-      // global login
+      // Global login
       matchHost: 'registry.gitlab.com',
       hostType: 'docker',
       username: '<some-username>',
       password: '<some-password>',
     },
     {
-      // for repository string oci://registry.gitlab.com/user/oci-helm-test
+      // For repository string oci://registry.gitlab.com/user/oci-helm-test
       matchHost: 'https://registry.gitlab.com/user/oci-helm-test',
       hostType: 'docker',
       username: '<some-username>',
@@ -48,14 +52,14 @@ For this you use a custom `hostRules` array.
 {
   hostRules: [
     {
-      // global login for 'gitlab.com' if using Helm
+      // Global login for 'gitlab.com' if using Helm
       matchHost: 'gitlab.com',
-      hostType: 'helm', // this is optional, but else the credentials will be used for all request matching `matchHost`
+      hostType: 'helm', // this is optional, but else the credentials will be used for all requests matching `matchHost`
       username: '<some-username>',
       password: '<some-password>',
     },
     {
-      // specific repository
+      // Specific repository
       matchHost: 'https://gitlab.com/api/v4/projects/xxxxxxx/packages/helm/stable',
       hostType: 'helm', // this is optional
       username: '<some-username>',