Add a series of technical guides to the project

[sugmanue]

Issue #, if available:

Add a series of technical guides to the project

Description of changes:

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[timocov]

Hey @sugmanue, may I ask your/the team vision this method. Currently it is marked as protected and I understand that the main purpose of this is to allow derived "impl" classes to call it, but also in theory it is possible to override it during the codegen to have some extra logic in it (and still call the original method from the base-class):

<I extends SerializableStruct, O extends SerializableStruct> O call(
      I input,
      ApiOperation<I, O> operation,
      RequestOverrideConfig overrideConfig
  ) {
    // some logic here
    return super.call(input, operation, overrideConfig);
  }

If you think that this is a possibility, would it be possible to expose RequestOverrideConfig fields to external consumers (or at least context getter)? Currently every getter in this class is package-private so it is not possible to access them from the outside (e.g. to get the context which was previously set by custom settings set by defaultSettings (similar to

smithy-java/examples/dynamodb-client/smithy-build.json

Lines 9 to 11 in b9d6559

	"defaultSettings": [
	"software.amazon.smithy.java.aws.client.auth.scheme.sigv4.SigV4Settings"
	],

). I understand that the main approach for this type of tasks should be using an interceptor, but when integrating into an existing system it is not always possible and some libraries require to wrap a call so that the context is correctly "scoped". Otherwise it would require either consumers to wrap every client call manually (which is prone to errors) or doing a refactoring on such libraries to allow to "split" their logic into separate phases (how the interceptor works).

Thanks!