Error in untested tutorial Markdown file

[echeran]

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There is a Markdown currently called data-management.md, soon to be renamed to date-picker-data.md, that is not being tested. I accidentally included it in the list of tests in tools/md-tests/src/lib.rs, and it results in a few errors. Ex:

---- tools/md-tests/src/lib.rs - tutorials::data_management_md (line 176) stdout ----
error[E0412]: cannot find type `Gregorian` in this scope
 --> tools/md-tests/src/lib.rs:177:43
  |
3 | let date_formatter = TypedDateFormatter::<Gregorian>::try_new_with_length(
  |                                           ^^^^^^^^^ not found in this scope
  |
help: you might be missing a type parameter
  |
2 | fn main() { #[allow(non_snake_case)] fn _doctest_main_tools_md_tests_src_lib_rs_176_0<Gregorian>() {
  |                                                                                      +++++++++++

...

[sffc]

We should make sure that all of our tutorial md files are being tested.