docs: remove "TBD" sections

The HOWTO documentation had a couple "TBD" sections for reporting bugs
or getting involved.

We already say how get involved in the first paragraph of the
documentation, so we do not need these "under construction" sections.

docs/source/HOWTO.rst

@@ -76,8 +76,6 @@ Installing the Koji cli
 There is a single point of entry for most operations. The command is
 called 'koji' and is included in the main koji package.
 
-Repos/webpage TBD
-
 The koji tool authenticates to the central server using Kerberos, so you
 will need to have a valid Kerberos ticket to use many features. However,
 many of the read-only commands will work without authentication.
@@ -155,11 +153,6 @@ there is a build.log, start there. Otherwise, look at init.log
           <topdir>/work/tasks/420066/root.log
 
 
-Filing Bugs
------------
-
-bug tracking TBD
-
 Koji Architecture
 =================
 
@@ -331,10 +324,3 @@ line tool will print a list of valid commands and each command supports
       --scratch             Perform a scratch build
       --nowait              Don't wait on build
     ...
-
-Getting Involved
-================
-
-If you would like to be more involved with the Koji project...
-
-Project data TBD