Adjust some documentation

Make it more clear that --compatibility only changes the default, it
doesn't override other compression options

doc/createrepo_c.8

@@ -182,7 +182,7 @@ Keep all additional metadata (not primary, filelists and other xml or sqlite fil
 Discard all additional metadata (not primary, filelists and other xml or sqlite files, nor their compressed variants) from source repository during update.
 .SS \-\-compatibility
 .sp
-Enforce maximal compatibility with classical createrepo (Changes \-\-retain\-old\-md behavior, uses Gzip for compression).
+Enforce maximal compatibility with classical createrepo (Changes \-\-retain\-old\-md behavior, defaults to Gzip for compression).
 .SS \-\-retain\-old\-md\-by\-age AGE
 .sp
 During \-\-update, remove all files in repodata/ which are older then the specified period of time. (e.g. \(aq2h\(aq, \(aq30d\(aq, ...). Available units (m \- minutes, h \- hours, d \- days)

src/cmd_parser.c

@@ -204,7 +204,7 @@ static GOptionEntry cmd_entries[] =
       "Discard all additional metadata (not primary, filelists and other xml or sqlite files, "
       "nor their compressed variants) from source repository during update.", NULL },
     { "compatibility", 0, 0, G_OPTION_ARG_NONE, &(_cmd_options.compatibility),
-      "Enforce maximal compatibility with classical createrepo and yum (Changes --retain-old-md behavior, uses Gzip for compression, produces sqlite metadata by default, leaves group metadata uncompressed).", NULL },
+      "Enforce maximal compatibility with classical createrepo and yum (Changes --retain-old-md behavior, defaults to Gzip for compression, produces sqlite metadata by default, leaves group metadata uncompressed).", NULL },
     { "retain-old-md-by-age", 0, 0, G_OPTION_ARG_STRING, &(_cmd_options.retain_old_md_by_age),
       "During --update, remove all files in repodata/ which are older "
       "then the specified period of time. (e.g. '2h', '30d', ...). "