add fingerprint analyzer docs (#8537) (#8920)

_analyzers/fingerprint.md

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+---
+layout: default
+title: Fingerprint analyzer
+nav_order: 110
+---
+
+# Fingerprint analyzer
+
+The `fingerprint` analyzer creates a text fingerprint. The analyzer sorts and deduplicates the terms (tokens) generated from the input and then concatenates them using a separator. It is commonly used for data deduplication because it produces the same output for similar inputs containing the same words, regardless of word order.
+
+The `fingerprint` analyzer comprises the following components:
+
+- Standard tokenizer
+- Lowercase token filter
+- ASCII folding token filter
+- Stop token filter
+- Fingerprint token filter
+
+## Parameters
+
+The `fingerprint` analyzer can be configured with the following parameters.
+
+Parameter | Required/Optional | Data type | Description
+:--- | :--- | :--- | :--- 
+`separator` | Optional | String | Specifies the character used to concatenate the terms after they have been tokenized, sorted, and deduplicated. Default is an empty space (` `).
+`max_output_size` | Optional | Integer | Defines the maximum size of the output token. If the concatenated fingerprint exceeds this size, it will be truncated. Default is `255`.
+`stopwords` | Optional | String or list of strings | A custom or predefined list of stopwords. Default is `_none_`.
+`stopwords_path` | Optional | String | The path (absolute or relative to the config directory) to the file containing a list of stopwords.
+
+
+## Example
+
+Use the following command to create an index named `my_custom_fingerprint_index` with a `fingerprint` analyzer:
+
+```json
+PUT /my_custom_fingerprint_index
+{
+  "settings": {
+    "analysis": {
+      "analyzer": {
+        "my_custom_fingerprint_analyzer": {
+          "type": "fingerprint",
+          "separator": "-",
+          "max_output_size": 50,
+          "stopwords": ["to", "the", "over", "and"]
+        }
+      }
+    }
+  },
+  "mappings": {
+    "properties": {
+      "my_field": {
+        "type": "text",
+        "analyzer": "my_custom_fingerprint_analyzer"
+      }
+    }
+  }
+}
+```
+{% include copy-curl.html %}
+
+## Generated tokens
+
+Use the following request to examine the tokens generated using the analyzer:
+
+```json
+POST /my_custom_fingerprint_index/_analyze
+{
+  "analyzer": "my_custom_fingerprint_analyzer",
+  "text": "The slow turtle swims over to the dog"
+}
+```
+{% include copy-curl.html %}
+
+The response contains the generated tokens:
+
+```json
+{
+  "tokens": [
+    {
+      "token": "dog-slow-swims-turtle",
+      "start_offset": 0,
+      "end_offset": 37,
+      "type": "fingerprint",
+      "position": 0
+    }
+  ]
+}
+```
+
+## Further customization
+
+If further customization is needed, you can define an analyzer with additional `fingerprint` analyzer components:
+
+```json
+PUT /custom_fingerprint_analyzer
+{
+  "settings": {
+    "analysis": {
+      "analyzer": {
+        "custom_fingerprint": {
+          "tokenizer": "standard",
+          "filter": [
+            "lowercase",
+            "asciifolding",
+            "fingerprint"
+          ]
+        }
+      }
+    }
+  }
+}
+```
+{% include copy-curl.html %}