Add references to AddonTemplate localization guides (#20332)
### Link to issue number
None
### Summary of the issue
Documentation about add-on localization was recently added to the
AddonTemplate repository. Relevant NVDA documentation pages did not yet
reference these new resources.
### Description of user facing changes
Added references to the AddonTemplate localization documentation for
add-on authors and translators.
### Description of developer facing changes
Developers and translators can now discover the add-on localization
documentation directly from the NVDA documentation.
### Description of development approach
Updated the following documentation pages to reference the localization
guides recently added to the AddonTemplate repository:
* `projectDocs/dev/addons.md`
* `projectDocs/translating/readme.md`
This work follows feedback provided during the review of
[nvaccess/addon-dataStore#9671](https://github.com/nvaccess/addon-dataStore/pull/9671).
As part of that discussion, it was suggested that the NVDA documentation
should reference the new add-on localization guides hosted in the
AddonTemplate repository, replacing outdated references to the old
TranslatingAddons wiki page.
### Testing strategy
Verified that all added links point to the correct AddonTemplate
documentation and that the modified Markdown renders correctly.
### Known issues with pull request
None
### Checklist
* [x] This change only affects documentation.
* [x] Documentation has been updated accordingly.
* [x] All added links have been verified.
* [x] Markdown formatting has been reviewed.
* [x] No code changes are included in this pull request.
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Co-authored-by: Sean Budd <seanbudd123@gmail.com>
