Update README: dating as strings

README.md

@@ -26,9 +26,9 @@ dataset_info:
   - name: translation
     dtype: string
   - name: dateNotBefore
-    dtype: int8
+    dtype: string
   - name: dateNotAfter
-    dtype: int8
+    dtype: string
   - name: authors
     dtype: string
 splits:
@@ -95,7 +95,7 @@ The dataset comes as a _JSON lines_ file.
 - `lemmatization`: a `string`, individual [TLA Lemma IDs](https://thesaurus-linguae-aegyptiae.de/info/lemma-lists)+"`|`"+lemma transliteration, separated by space.
 - `transliteration`: a `string`, individual glosses separated by space (for information, see the comments below).
 - `translation`:  a `string`, German translation.
-- `dateNotBefore`, `dateNotAfter`: two integers (`int8`) or `null`, termini ante quem not and post quem non for the text witness.
+- `dateNotBefore`, `dateNotAfter`: two `strings` containing an integer or empty, _terminus ante quem non_ and _terminus post quem non_ for the text witness.
 - `authors`: a `string`, main authors and further contributors to the sentence data set, individual items separated by `;`.
 
 ### Data instances
@@ -108,8 +108,8 @@ Example of an dataset instance:
   "UPOS": "VERB ADP NOUN PRON",
   "glossing": "V PREP N.m -2sg.m",
   "translation": "Komm in dein Haus!",
-  "dateNotBefore": -75,
-  "dateNotAfter": -51,
+  "dateNotBefore": "-75",
+  "dateNotAfter": "-51",
   "authors": "Günter Vittmann;AV Altägyptisches Wörterbuch, AV Wortschatz der ägyptischen Sprache"
 }
 ```