[DOCS] Reformat elision token filter docs (#49262)

docs/reference/analysis/tokenfilters/elision-tokenfilter.asciidoc

@@ -1,15 +1,96 @@
 [[analysis-elision-tokenfilter]]
-=== Elision Token Filter
+=== Elision token filter
+++++
+<titleabbrev>Elision</titleabbrev>
+++++
 
-A token filter which removes elisions. For example, "l'avion" (the
-plane) will tokenized as "avion" (plane).
+Removes specified https://en.wikipedia.org/wiki/Elision[elisions] from
+the beginning of tokens. For example, you can use this filter to change
+`l'avion` to `avion`.
 
-Requires either an `articles` parameter which is a set of stop word articles, or
-`articles_path` which points to a text file containing the stop set. Also optionally
-accepts `articles_case`, which indicates whether the filter treats those articles as
-case sensitive.
+When not customized, the filter removes the following French elisions by default:
 
-For example:
+`l'`, `m'`, `t'`, `qu'`, `n'`, `s'`, `j'`, `d'`, `c'`, `jusqu'`, `quoiqu'`,
+`lorsqu'`, `puisqu'`
+
+Customized versions of this filter are included in several of {es}'s built-in
+<<analysis-lang-analyzer,language analyzers>>:
+
+* <<catalan-analyzer, Catalan analyzer>>
+* <<french-analyzer, French analyzer>>
+* <<irish-analyzer, Irish analyzer>>
+* <<italian-analyzer, Italian analyzer>>
+
+This filter uses Lucene's
+https://lucene.apache.org/core/{lucene_version_path}/analyzers-common/org/apache/lucene/analysis/util/ElisionFilter.html[ElisionFilter].
+
+[[analysis-elision-tokenfilter-analyze-ex]]
+==== Example
+
+The following <<indices-analyze,analyze API>> request uses the `elision`
+filter to remove `j'` from `j’examine près du wharf`:
+
+[source,console]
+--------------------------------------------------
+GET _analyze
+{
+  "tokenizer" : "standard",
+  "filter" : ["elision"],
+  "text" : "j’examine près du wharf"
+}
+--------------------------------------------------
+
+The filter produces the following tokens:
+
+[source,text]
+--------------------------------------------------
+[ examine, près, du, wharf ]
+--------------------------------------------------
+
+/////////////////////
+[source,console-result]
+--------------------------------------------------
+{
+  "tokens" : [
+    {
+      "token" : "examine",
+      "start_offset" : 0,
+      "end_offset" : 9,
+      "type" : "<ALPHANUM>",
+      "position" : 0
+    },
+    {
+      "token" : "près",
+      "start_offset" : 10,
+      "end_offset" : 14,
+      "type" : "<ALPHANUM>",
+      "position" : 1
+    },
+    {
+      "token" : "du",
+      "start_offset" : 15,
+      "end_offset" : 17,
+      "type" : "<ALPHANUM>",
+      "position" : 2
+    },
+    {
+      "token" : "wharf",
+      "start_offset" : 18,
+      "end_offset" : 23,
+      "type" : "<ALPHANUM>",
+      "position" : 3
+    }
+  ]
+}
+--------------------------------------------------
+/////////////////////
+
+[[analysis-elision-tokenfilter-analyzer-ex]]
+==== Add to an analyzer
+
+The following <<indices-create-index,create index API>> request uses the
+`elision` filter to configure a new 
+<<analysis-custom-analyzer,custom analyzer>>.
 
 [source,console]
 --------------------------------------------------
@@ -18,16 +99,85 @@ PUT /elision_example
     "settings" : {
         "analysis" : {
             "analyzer" : {
-                "default" : {
-                    "tokenizer" : "standard",
+                "whitespace_elision" : {
+                    "tokenizer" : "whitespace",
                     "filter" : ["elision"]
                 }
+            }
+        }
+    }
+}
+--------------------------------------------------
+
+[[analysis-elision-tokenfilter-configure-parms]]
+==== Configurable parameters
+
+[[analysis-elision-tokenfilter-articles]]
+`articles`::
++
+--
+(Required+++*+++, array of string)
+List of elisions to remove.
+
+To be removed, the elision must be at the beginning of a token and be
+immediately followed by an apostrophe. Both the elision and apostrophe are
+removed.
+
+For custom `elision` filters, either this parameter or `articles_path` must be
+specified.
+--
+
+`articles_path`::
++
+--
+(Required+++*+++, string)
+Path to a file that contains a list of elisions to remove.
+
+This path must be absolute or relative to the `config` location, and the file
+must be UTF-8 encoded. Each elision in the file must be separated by a line
+break.
+
+To be removed, the elision must be at the beginning of a token and be
+immediately followed by an apostrophe. Both the elision and apostrophe are
+removed.
+
+For custom `elision` filters, either this parameter or `articles` must be
+specified.
+--
+
+`articles_case`::
+(Optional, boolean)
+If `true`, the filter treats any provided elisions as case sensitive.
+Defaults to `false`.
+
+[[analysis-elision-tokenfilter-customize]]
+==== Customize
+
+To customize the `elision` filter, duplicate it to create the basis
+for a new custom token filter. You can modify the filter using its configurable
+parameters.
+
+For example, the following request creates a custom case-sensitive `elision`
+filter that removes the `l'`, `m'`, `t'`, `qu'`, `n'`, `s'`,
+and `j'` elisions:
+
+[source,console]
+--------------------------------------------------
+PUT /elision_case_sensitive_example
+{
+    "settings" : {
+        "analysis" : {
+            "analyzer" : {
+                "default" : {
+                    "tokenizer" : "whitespace",
+                    "filter" : ["elision_case_sensitive"]
+                }
             },
             "filter" : {
-                "elision" : {
+                "elision_case_sensitive" : {
                     "type" : "elision",
-                    "articles_case": true,
-                    "articles" : ["l", "m", "t", "qu", "n", "s", "j"]
+                    "articles" : ["l", "m", "t", "qu", "n", "s", "j"],
+                    "articles_case": true
                 }
             }
         }