Use globally unique Doxygen group names

This is necessary to avoid clashes when building unified documentation as a
subproject.

doc/c/overview.rst

@@ -5,14 +5,14 @@ Overview
 .. default-domain:: c
 .. highlight:: c
 
-The API revolves around two main types: the :doc:`api/reader`,
+The API revolves around two main types: the :doc:`api/serd_reader`,
 which reads text and fires callbacks,
-and the :doc:`api/writer`,
+and the :doc:`api/serd_writer`,
 which writes text when driven by corresponding functions.
 Both work in a streaming fashion but still support pretty-printing,
 so the pair can be used to pretty-print, translate,
 or otherwise process arbitrarily large documents very quickly.
-The context of a stream is tracked by the :doc:`api/env`,
+The context of a stream is tracked by the :doc:`api/serd_env`,
 which stores the current base URI and set of namespace prefixes.
 
 The complete API is declared in ``serd.h``:

include/serd/serd.h

@@ -263,7 +263,7 @@ void
 serd_free(void* SERD_NULLABLE ptr);
 
 /**
-   @defgroup string String Utilities
+   @defgroup serd_string String Utilities
    @{
 */
 
@@ -317,7 +317,7 @@ serd_base64_decode(const uint8_t* SERD_NONNULL str,
 
 /**
    @}
-   @defgroup streams Byte Streams
+   @defgroup serd_streams Byte Streams
    @{
 */
 
@@ -354,7 +354,7 @@ typedef size_t (*SerdSink)(const void* SERD_NONNULL buf,
 
 /**
    @}
-   @defgroup uri URI
+   @defgroup serd_uri URI
    @{
 */
 
@@ -432,7 +432,7 @@ serd_uri_serialise_relative(const SerdURI* SERD_NONNULL  uri,
 
 /**
    @}
-   @defgroup node Node
+   @defgroup serd_node Node
    @{
 */
 
@@ -590,7 +590,7 @@ serd_node_free(SerdNode* SERD_NULLABLE node);
 
 /**
    @}
-   @defgroup event Event Handlers
+   @defgroup serd_event Event Handlers
    @{
 */
 
@@ -647,7 +647,7 @@ typedef SerdStatus (*SerdEndSink)(void* SERD_NULLABLE          handle,
 
 /**
    @}
-   @defgroup env Environment
+   @defgroup serd_env Environment
    @{
 */
 
@@ -733,7 +733,7 @@ serd_env_foreach(const SerdEnv* SERD_NONNULL env,
 
 /**
    @}
-   @defgroup reader Reader
+   @defgroup serd_reader Reader
    @{
 */
 
@@ -885,7 +885,7 @@ serd_reader_free(SerdReader* SERD_NULLABLE reader);
 
 /**
    @}
-   @defgroup writer Writer
+   @defgroup serd_writer Writer
    @{
 */