doc: add documentation to all the public structs and enumscmn/doc-all

This makes them show up in the reference, even if the text itself isn't
the most descriptive.

These have been found with

    grep -Przon '\n\ntypedef struct.*?\{' -- include
    grep -Przon '\n\ntypedef enum.*?\{' -- include

1 files changed, 12 insertions, 3 deletions

diff --git a/include/git2/config.h b/include/git2/config.h
index 1fd98b200..e32c614ea 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -55,15 +55,21 @@ typedef enum {
 	GIT_CONFIG_HIGHEST_LEVEL = -1,
 } git_config_level_t;
 
+/**
+ * An entry in a configuration file
+ */
 typedef struct {
-	const char *name;
-	const char *value;
-	git_config_level_t level;
+	const char *name; /*< Name of the entry (normalised) */
+	const char *value; /*< String value of the entry */
+	git_config_level_t level; /*< Which config file this was found in */
 } git_config_entry;
 
 typedef int  (*git_config_foreach_cb)(const git_config_entry *, void *);
 typedef struct git_config_iterator git_config_iterator;
 
+/**
+ * Config var type
+ */
 typedef enum {
 	GIT_CVAR_FALSE = 0,
 	GIT_CVAR_TRUE = 1,
@@ -71,6 +77,9 @@ typedef enum {
 	GIT_CVAR_STRING
 } git_cvar_t;
 
+/**
+ * Mapping from config variables to values.
+ */
 typedef struct {
 	git_cvar_t cvar_type;
 	const char *str_match;