Update docs with new 'Get*ClientOptions()' overloads for Azure builders. (#208)

Author: StephenMolloy

README.md

@@ -28,8 +28,9 @@ linked here:
         object being created by `ConfigurationManager.OpenConfiguration*` API's rather than being part of a fully-initialized runtime configuration stack.
   * Json use has migrated to use `System.Text.Json` instead of `Newtonsoft.Json`.
   * The [Azure Config Builders](#azure-config-builders) have been updated to require a newer minimum version of `Azure.Identity` by default which allows for more
-        methods of connecting to Azure, such as **User-Assigned Managed Identity**, or **Client Certificate-based** via environment variables. An overload named
-        `GetCredential` has also been added for users who need something more custom than upgrading `Azure.Identity` can easily provide.
+        methods of connecting to Azure, such as **User-Assigned Managed Identity**, or **Client Certificate-based** via environment variables. Also a pair of overloads
+        (`GetCredential` and `GetSecretClientOptions/GetConfigurationClientOptions`) have been added for users who need something more than `DefaultAzureCredential`
+        with default client options can provide.
   * Added *RecursionGuard* to help detect and prevent situations where a `ConfigurationBuilder` accessing values from a `ConfigurationSection` other than the one
         which it is currently processing could result in stack overflow.
   * `optional` attribute is obsolete => [`enabled`](docs/KeyValueConfigBuilders.md#enabled) attribute which provides more versatility. (The `optional` attribute is still parsed and recognized in the absence

docs/KeyValueConfigBuilders.md

@@ -184,6 +184,10 @@ to read the necessary options for these methods via environment variables. Build
 their Azure credential for these builders can extend and override the `GetCredential()` method of either builder to supply the correct
 `TokenCredential` for connecting to Azure.
 
+In a similar vein to `GetCredential()`, builders who need finer control over the way it connects to Azure, the `GetConfigurationClientOptions()`
+and `GetSecretClientOptions()` virtual methods have been added to the Azure config builders to support special scenarios. (For
+example, connecting to Azure through a proxy.)
+
 NOTE: These packages both currently depend on version ***1.2*** of the `Azure.Identity` nuget package. This version was chosen because
 it has a fairly comprehensive list of capabilities for `DefaultAzureCredential` but also is a relatively early version of this SDK package.
 This way these builders won't be responsible for forcing unwanted package upgrades when not necessary. However, `DefaultAzureCredential`