[v3] Extract Concepts from v2 exercise: circular-buffer

Extract the list of concepts required to solve the v2 C++ exercise: `circular-buffer`. For each concept, describe why it is required to solve the exercise. Keep in mind that an exercise can have multiple approaches (you can find community solutions here: `https://exercism.io/tracks/cpp/exercises/circular-buffer/solutions`). The goal of this task is to help determine the total list of concepts that make up `circular-buffer`.

The list of concepts should be stored in the following document: `languages/cpp/reference/exercise-concepts/circular-buffer.md`. [Use this link to create a PR to add this document][pr-link].

[pr-link]: ../new/master?filename=languages/cpp/reference/exercise-concepts/circular-buffer.md

Comienza leyendo el ejercicio de v2 C++ sobre circular-buffer y revisando las soluciones de la comunidad enlazadas para conocer enfoques alternativos. Registra los conceptos necesarios para esos enfoques en languages/cpp/reference/exercise-concepts/circular-buffer.md, con una descripción de por qué se necesita cada concepto; se considera terminado cuando el documento cubre la lista completa de conceptos.

Escrito por el modelo de indexación a partir del texto del issue.