Update wording in LDA docs

[ericstj]

Update the wording mentioning countries. This is actually a quote, but it need not mention countries - the actual source of this quote has since been updated.
https://en.wikipedia.org/w/index.php?title=Earth_Day&oldid=824511329 (which was pulled from an old version of earthday.org).

I didn't bother updating the values in the comment - I'm not sure if they need to be accurate to get the point across. @michaelgsharp if you think they should be updated please let me know and help me recompute them.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 68.78%. Comparing base (be1e428) to head (532de28). Report is 8 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #7253 +/- ## ========================================== + Coverage 68.77% 68.78% +0.01% ========================================== Files 1462 1463 +1 Lines 272261 272288 +27 Branches 28176 28177 +1 ========================================== + Hits 187254 187304 +50 + Misses 77764 77741 -23 Partials 7243 7243 ``` | [Flag](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | Coverage Δ | | |---|---|---| | [Debug](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `68.78% <ø> (+0.01%)` | :arrow_up: | | [production](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `63.29% <ø> (+0.01%)` | :arrow_up: | | [test](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | `89.04% <ø> (+<0.01%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files with missing lines](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet) | Coverage Δ | | |---|---|---| | [src/Microsoft.ML.Transforms/Text/LdaTransform.cs](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253?src=pr&el=tree&filepath=src%2FMicrosoft.ML.Transforms%2FText%2FLdaTransform.cs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet#diff-c3JjL01pY3Jvc29mdC5NTC5UcmFuc2Zvcm1zL1RleHQvTGRhVHJhbnNmb3JtLmNz) | `88.44% <ø> (ø)` | | ... and [10 files with indirect coverage changes](https://app.codecov.io/gh/dotnet/machinelearning/pull/7253/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dotnet)

[ericstj]

Failure downloading tokenizer vocab file