Removed hyperlink to tlaplus-standard repo

Signed-off-by: Andrew Helwer <ahelwer@pm.me>

Author: ahelwer

DEVELOPING.md

@@ -13,7 +13,7 @@ Here is a brief overview of each script in the order they are run in [the CI](.g
 1. [`check_manifest_files.py`](.github/scripts/check_manifest_files.py): this ensures the modules & models recorded in [`manifest.json`](manifest.json) concord with the set of modules & models found under the [`specifications`](specifications) directory, while also respecting the exclusion of any specs in the [`.ciignore`](.ciignore) file.
 1. [`check_manifest_features.py`](.github/scripts/check_manifest_features.py`): this uses the [tree-sitter-tlaplus](https://pypi.org/project/tree-sitter-tlaplus/) python package to run queries on all the `.tla` files and ensure their features (`proof`, `pluscal`, `action composition`) are correctly recorded in [`manifest.json`](manifest.json); it also does best-effort regex parsing of all `.cfg` files to ensure their features (`view`, `alias`, etc.) are similarly correctly recorded.
 1. [`check_markdown_table.py`](.github/scripts/check_markdown_table.py): this uses the [mistletoe](https://pypi.org/project/mistletoe/) markdown parser python package to parse [`README.md`](README.md), extract the spec table, then validate its format & contents against [`manifest.json`](manifest.json); before this script was developed the table tended to diverge wildly from the actual content of this repo.
-1. [`unicode_conversion.py`](.github/scripts/unicode_conversion.py): this script uses [tlauc](https://github.com/tlaplus-community/tlauc) to convert each spec into its [Unicode](https://github.com/tlaplus/tlaplus-standard/tree/652a8eb5d5838b9712be3502cb36dbae826d5689/unicode) form to ensure TLA⁺ tooling functions identically on ASCII & Unicode specs.
+1. [`unicode_conversion.py`](.github/scripts/unicode_conversion.py): this script uses [tlauc](https://github.com/tlaplus-community/tlauc) to convert each spec into its Unicode form to ensure TLA⁺ tooling functions identically on ASCII & Unicode specs.
    The CI spawns separate runs with and without conversion of specs to Unicode.
 1. [`unicode_number_set_shim.py`](.github/scripts/unicode_number_set_shim.py): since Unicode adoption is not yet fully ratified, Unicode definitions like `ℕ`, `ℤ`, and `ℝ` (as synonyms for `Nat`, `Int`, and `Real` respectively) are not yet included in the standard modules.
    This script works around that by using the [tree-sitter-tlaplus](https://pypi.org/project/tree-sitter-tlaplus/) python package to rewrite all imports of the `Naturals`, `Integers`, and `Reals` modules to import shim modules instead that define `ℕ`, `ℤ`, and `ℝ`.