Revert "migrate docs to mdx"

This reverts commit 3cb12b5a52.

website/docs/language/functions/can.mdx

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----
-page_title: can - Functions - Configuration Language
-description: |-
-  The can function tries to evaluate an expression given as an argument and
-  indicates whether the evaluation succeeded.
-sidebar_title: can
----
-
-# `can` Function
-
-`can` evaluates the given expression and returns a boolean value indicating
-whether the expression produced a result without any errors.
-
-This is a special function that is able to catch errors produced when evaluating
-its argument. For most situations where you could use `can` it's better to use
-[`try`](/language/functions/try) instead, because it allows for more concise definition of
-fallback values for failing expressions.
-
-The primary purpose of `can` is to turn an error condition into a boolean
-validation result when writing
-[custom variable validation rules](/language/values/variables#custom-validation-rules).
-For example:
-
-```
-variable "timestamp" {
-  type        = string
-
-  validation {
-    # formatdate fails if the second argument is not a valid timestamp
-    condition     = can(formatdate("", var.timestamp))
-    error_message = "The timestamp argument requires a valid RFC 3339 timestamp."
-  }
-}
-```
-
-The `can` function can only catch and handle _dynamic_ errors resulting from
-access to data that isn't known until runtime. It will not catch errors
-relating to expressions that can be proven to be invalid for any input, such
-as a malformed resource reference.
-
-~> **Warning:** The `can` function is intended only for simple tests in
-variable validation rules. Although it can technically accept any sort of
-expression and be used elsewhere in the configuration, we recommend against
-using it in other contexts. For error handling elsewhere in the configuration,
-prefer to use [`try`](/language/functions/try).
-
-## Examples
-
-```
-> local.foo
-{
-  "bar" = "baz"
-}
-> can(local.foo.bar)
-true
-> can(local.foo.boop)
-false
-```
-
-The `can` function will _not_ catch errors relating to constructs that are
-provably invalid even before dynamic expression evaluation, such as a malformed
-reference or a reference to a top-level object that has not been declared:
-
-```
-> can(local.nonexist)
-
-Error: Reference to undeclared local value
-
-A local value with the name "nonexist" has not been declared.
-```
-
-## Related Functions
-
-* [`try`](/language/functions/try), which tries evaluating a sequence of expressions and
-  returns the result of the first one that succeeds.