Document or mitigate undesired number formatting in `values.yaml`

[0x2b3bfa0]

When e.g. global.scmProviders.github.appId is specified as a YAML number, rather than as a YAML string, it gets mangled by Helm and converted into scientific notation.

We should document this undesired behavior, or maybe even mitigate it for this specific field.

Correct syntax

global:
  scmProviders:
    github:
      appId: "1200981"

Upstream issue

• --set parses number only values as float64 helm/helm#1707