lib: add some missing version tags

src/libostree/ostree-repo-commit.c

@@ -4332,6 +4332,8 @@ ostree_repo_commit_modifier_set_sepolicy (OstreeRepoCommitModifier
  * In many cases, one wants to create a "derived" commit from base commit.
  * SELinux policy labels are part of that base commit.  This API allows
  * one to easily set up SELinux labeling from a base commit.
+ *
+ * Since: 2020.4
  */
 gboolean 
 ostree_repo_commit_modifier_set_sepolicy_from_commit (OstreeRepoCommitModifier              *modifier,

src/libostree/ostree-sign.c

@@ -593,6 +593,8 @@ ostree_sign_get_by_name (const gchar *name, GError **error)
  * Based on ostree_repo_add_gpg_signature_summary implementation.
  *
  * Returns: @TRUE if summary file has been signed with all provided keys
+ *
+ * Since: 2020.2
  */
 gboolean
 ostree_sign_summary (OstreeSign    *self,

src/libostree/ostree-sign.h

@@ -52,6 +52,8 @@ G_GNUC_END_IGNORE_DEPRECATIONS
 /**
  * OSTREE_SIGN_NAME_ED25519:
  * The name of the default ed25519 signing type.
+ *
+ * Since: 2020.4
  */
 #define OSTREE_SIGN_NAME_ED25519 "ed25519"