docs: fix some comment-marker typos

include/git2/blame.h

@@ -128,7 +128,7 @@ typedef struct git_blame_hunk {
 } git_blame_hunk;
 
 
-/* Opaque structure to hold blame results */
+/** Opaque structure to hold blame results */
 typedef struct git_blame git_blame;
 
 /**

include/git2/repository.h

@@ -368,7 +368,7 @@ GIT_EXTERN(int) git_repository_head_for_worktree(git_reference **out, git_reposi
  */
 GIT_EXTERN(int) git_repository_head_detached(git_repository *repo);
 
-/*
+/**
  * Check if a worktree's HEAD is detached
  *
  * A worktree's HEAD is detached when it points directly to a

include/git2/types.h

@@ -215,7 +215,7 @@ typedef enum {
 	GIT_FILEMODE_COMMIT              = 0160000,
 } git_filemode_t;
 
-/*
+/**
  * A refspec specifies the mapping between remote and local reference
  * names when fetch or pushing.
  */