Clean unmaintained Ubuntu versions

doc/sources/admin/documentation.rst

@@ -86,9 +86,6 @@ Ubuntu dist               LLNG version                     Secured
 14.04       Trusty        `1.2.5 </documentation/1.2/>`__  |maybe| No known vulnerability                                       None
 16.04       Xenial  [9]_  `1.4.6 </documentation/1.4/>`__  |bad| CVE-2019-12046, CVE-2019-13031                                 None
 18.04       Bionic  [9]_  `1.9.16 </documentation/1.9/>`__ |bad| CVE-2019-12046, CVE-2019-13031, CVE-2020-24660                 None
-18.10       Cosmic        `1.9.17 </documentation/1.9/>`__ |bad| CVE-2019-12046, CVE-2019-13031, CVE-2020-24660                 None
-19.04       Disco         `2.0.2 </documentation/2.0/>`__  |bad| CVE-2019-12046, CVE-2019-13031, CVE-2019-15941, CVE-2020-24660 None
-19.10       Eoan          `2.0.5 </documentation/2.0/>`__  |bad| CVE-2019-15941, CVE-2020-24660                                 None
 20.04       Focal  [9]_   `2.0.7 </documentation/2.0/>`__  |bad| CVE-2020-24660                                                 None
 20.10       Groovy        `2.0.8 </documentation/2.0/>`__  |bad| CVE-2020-24660                                                 None
 21.04       Hirsute       `2.0.11 </documentation/2.0/>`__ |clean|                                                              None