Add decimal digit token filter docs #7923 (#7977) (#8657)

_analyzers/token-filters/decimal-digit.md

@@ -0,0 +1,88 @@
+---
+layout: default
+title: Decimal digit
+parent: Token filters
+nav_order: 80
+---
+
+# Decimal digit token filter
+
+The `decimal_digit` token filter is used to normalize decimal digit characters (0--9) into their ASCII equivalents in various scripts. This is useful when you want to ensure that all digits are treated uniformly in text analysis, regardless of the script in which they are written.
+
+
+## Example
+
+The following example request creates a new index named `my_index` and configures an analyzer with a `decimal_digit` filter:
+
+```json
+PUT /my_index
+{
+  "settings": {
+    "analysis": {
+      "filter": {
+        "my_decimal_digit_filter": {
+          "type": "decimal_digit"
+        }
+      },
+      "analyzer": {
+        "my_analyzer": {
+          "type": "custom",
+          "tokenizer": "standard",
+          "filter": ["my_decimal_digit_filter"]
+        }
+      }
+    }
+  }
+}
+
+```
+{% include copy-curl.html %}
+
+## Generated tokens
+
+Use the following request to examine the tokens generated using the analyzer:
+
+```json
+POST /my_index/_analyze
+{
+  "analyzer": "my_analyzer",
+  "text": "123 ١٢٣ १२३"
+}
+```
+{% include copy-curl.html %}
+
+`text` breakdown:
+
+ - "123" (ASCII digits)
+ - "١٢٣" (Arabic-Indic digits)
+ - "१२३" (Devanagari digits)
+
+The response contains the generated tokens:
+
+```json
+{
+  "tokens": [
+    {
+      "token": "123",
+      "start_offset": 0,
+      "end_offset": 3,
+      "type": "<NUM>",
+      "position": 0
+    },
+    {
+      "token": "123",
+      "start_offset": 4,
+      "end_offset": 7,
+      "type": "<NUM>",
+      "position": 1
+    },
+    {
+      "token": "123",
+      "start_offset": 8,
+      "end_offset": 11,
+      "type": "<NUM>",
+      "position": 2
+    }
+  ]
+}
+```

_analyzers/token-filters/index.md

@@ -22,7 +22,7 @@ Token filter | Underlying Lucene token filter|  Description
 [`classic`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/classic) | [ClassicFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/classic/ClassicFilter.html) | Performs optional post-processing on the tokens generated by the classic tokenizer. Removes possessives (`'s`) and removes `.` from acronyms.
 [`common_grams`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/common_gram/) | [CommonGramsFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/commongrams/CommonGramsFilter.html) | Generates bigrams for a list of frequently occurring terms. The output contains both single terms and bigrams.
 `conditional` | [ConditionalTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ConditionalTokenFilter.html) | Applies an ordered list of token filters to tokens that match the conditions provided in a script.
-`decimal_digit` | [DecimalDigitFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/DecimalDigitFilter.html) | Converts all digits in the Unicode decimal number general category to basic Latin digits (0--9). 
+[`decimal_digit`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/decimal-digit/) | [DecimalDigitFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/DecimalDigitFilter.html) | Converts all digits in the Unicode decimal number general category to basic Latin digits (0--9). 
 `delimited_payload` | [DelimitedPayloadTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/payloads/DelimitedPayloadTokenFilter.html) | Separates a token stream into tokens with corresponding payloads, based on a provided delimiter. A token consists of all characters before the delimiter, and a payload consists of all characters after the delimiter. For example, if the delimiter is `|`, then for the string `foo|bar`, `foo` is the token and `bar` is the payload. 
 [`delimited_term_freq`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/delimited-term-frequency/) | [DelimitedTermFrequencyTokenFilter](https://lucene.apache.org/core/9_7_0/analysis/common/org/apache/lucene/analysis/miscellaneous/DelimitedTermFrequencyTokenFilter.html) | Separates a token stream into tokens with corresponding term frequencies, based on a provided delimiter. A token consists of all characters before the delimiter, and a term frequency is the integer after the delimiter. For example, if the delimiter is `|`, then for the string `foo|5`, `foo` is the token and `5` is the term frequency.
 `dictionary_decompounder` | [DictionaryCompoundWordTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/compound/DictionaryCompoundWordTokenFilter.html) | Decomposes compound words found in many Germanic languages.