[Docs] Add definitions to glossary (#29127)

Definitions for "filter" and "query" are added to the glossary of terms.

Closes #29127

docs/reference/glossary.asciidoc

@@ -61,6 +61,15 @@
   `object`. The mapping also allows you to define (amongst other things)
   how the value for a field should be analyzed.
 
+[[glossary-filter]] filter ::
+
+  A filter is a non-scoring <<glossary-query,query>>, meaning that it does not score documents.
+  It is only concerned about answering the question - "Does this document match?". 
+  The answer is always a simple, binary yes or no. This kind of query is said to be made 
+  in a <<query-filter-context,filter context>>, 
+  hence it is called a filter. Filters are simple checks for set inclusion or exclusion. 
+  In most cases, the goal of filtering is to reduce the number of documents that have to be examined.
+
 [[glossary-index]] index ::
 
   An index is like a _table_ in a relational database. It has a
@@ -105,6 +114,16 @@
   +
   See also <<glossary-routing,routing>>
 
+[[glossary-query]] query ::
+
+  A query is the basic component of a search. A search can be defined by one or more queries 
+  which can be mixed and matched in endless combinations. While <<glossary-filter,filters>> are
+  queries that only determine if a document matches, those queries that also calculate how well
+  the document matches are known as "scoring queries". Those queries assign it a score, which is 
+  later used to sort matched documents. Scoring queries take more resources than <<glossary-filter,non scoring queries>> 
+  and their query results are not cacheable. As a general rule, use query clauses for full-text 
+  search or for any condition that requires scoring, and use filters for everything else.
+
  [[glossary-replica-shard]] replica shard ::
 
   Each <<glossary-primary-shard,primary shard>> can have zero or more
@@ -161,8 +180,9 @@
 
   A term is an exact value that is indexed in Elasticsearch. The terms
   `foo`, `Foo`, `FOO` are NOT equivalent. Terms (i.e. exact values) can
-  be searched for using _term_ queries. +
-   See also <<glossary-text,text>> and <<glossary-analysis,analysis>>.
+  be searched for using _term_ queries.
+  +
+  See also <<glossary-text,text>> and <<glossary-analysis,analysis>>.
 
 [[glossary-text]] text ::