Clarify POST in free-text search

Author: m-mohr

README.md

@@ -64,11 +64,16 @@ These are aligned with the corresponding parameters in STAC API - Features and O
 
 - Conformance class: `https://api.stacspec.org/v1.0.0-rc.1/collection-search#free-text`
 
-A free-text search parameter `q` based on OGC API - Records can be added.
+A basic free-text search parameter `q` based on OGC API - Records can be added.
 See <https://docs.ogc.org/DRAFTS/20-004.html#_parameter_q> for details.
+
 The specific set of text fields of a Collection to which the parameter is applied is left to the discretion of the implementation, but a recommendation is to at least consider `title`, `description` and `keywords`.
 
-The search works case-insensitive. Any of the search terms must be present in the set of text fields. The operator is OR and all search terms must be delimited by a comma. Spaces have no special meaning. So if you want to search for "Earth Observation" or "EO", your query parameter should be as follows: `q=EO,Earth Observation`.
+The search works case-insensitive and spaces have no special meaning.
+Any of the search terms must be present in the set of text fields (OR operaror).
+
+- In HTTP `GET` requests, all search terms must be separated by a comma. For example, if you want to search for "Earth Observation" or "EO", your query parameter should be as follows: `q=EO,Earth Observation`.
+- In HTTP `POST` requests, an array of search terms must be provided, for example: `{"q": ["EO", "Earth Observation"]}`.
 
 #### Filter (CQL)