Explicit conversion example in docs should use `template get`

[tusooa]

Description

Follow up of #3827 .

As get<>() may not always work, the documentation SHOULD use template get<>() instead of get<>() in the examples to avoid confusion.

Reproduction steps

use the explicit conversion described in the example

Expected vs. actual results

expected: works

actual: compilation failure

Minimal code example

No response

Error messages

No response

Compiler and operating system

g++ 12 on GNU/Linux

Library version

3.11.2

Validation

• The bug also occurs if the latest version from the develop branch is used.
• I can successfully compile and run the unit tests.