Revert "migrate docs to mdx"

This reverts commit 3cb12b5a52.

website/docs/language/functions/filebase64.mdx

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----
-page_title: filebase64 - Functions - Configuration Language
-description: |-
-  The filebase64 function reads the contents of the file at the given path and
-  returns them as a base64-encoded string.
-sidebar_title: filebase64
----
-
-# `filebase64` Function
-
-`filebase64` reads the contents of a file at the given path and returns them as
-a base64-encoded string.
-
-```hcl
-filebase64(path)
-```
-
-The result is a Base64 representation of the raw bytes in the given file.
-Strings in the Terraform language are sequences of Unicode characters, so
-Base64 is the standard way to represent raw binary data that cannot be
-interpreted as Unicode characters. Resource types that operate on binary
-data will accept this data encoded in Base64, thus avoiding the need to
-decode the result of this function.
-
-Terraform uses the "standard" Base64 alphabet as defined in
-[RFC 4648 section 4](https://tools.ietf.org/html/rfc4648#section-4).
-
-This function can be used only with functions that already exist as static
-files on disk at the beginning of a Terraform run. Language functions do not
-participate in the dependency graph, so this function cannot be used with
-files that are generated dynamically during a Terraform operation.
-
-## Examples
-
-```
-> filebase64("${path.module}/hello.txt")
-SGVsbG8gV29ybGQ=
-```
-
-## Related Functions
-
-* [`file`](/language/functions/file) also reads the contents of a given file,
-  but interprets the data as UTF-8 text and returns the result directly
-  as a string, without any further encoding.
-* [`base64decode`](/language/functions/base64decode) can decode a Base64 string representing
-  bytes in UTF-8, but in practice `base64decode(filebase64(...))` is equivalent
-  to the shorter expression `file(...)`.