cgitrc.5.txt: reformat the "FILTER API" section

This patch makes the generated man-page for the filer api section more
similar to the other sections. Also, the bulleted list of environment
variables wasn't rendered correctly (with asciidoc 8.5.2), without an
empty line before the first item.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

cgitrc.5.txt

@@ -460,39 +460,37 @@ config files, e.g. "repo.desc" becomes "desc".
 
 FILTER API
 ----------
-- about filter::
-  This filter is given no arguments.
-  The about text that is to be filtered is available on standard input and the
-  filtered text is expected on standard output.
-- commit filter::
-  This filter is given no arguments.
-  The commit message text that is to be filtered is available on standard input
-  and the filtered text is expected on standard output.
-- source filter::
-  This filter is given a single parameter: the filename of the source file to
-  filter. The filter can use the filename to determine (for example) the syntax
-  highlighting mode.
-  The contents of the source file that is to be filtered is available on
-  standard input and the filtered contents is expected on standard output.
+about filter::
+	This filter is given no arguments. The about text that is to be
+	filtered is available on standard input and the filtered text is
+	expected on standard output.
+
+commit filter::
+	This filter is given no arguments. The commit message text that is to
+	be filtered is available on standard input and the filtered text is
+	expected on standard output.
+
+source filter::
+	This filter is given a single parameter: the filename of the source
+	file to filter. The filter can use the filename to determine (for
+	example) the syntax highlighting mode. The contents of the source
+	file that is to be filtered is available on standard input and the
+	filtered contents is expected on standard output.
 
 Also, all filters are handed the following environment variables:
-- CGIT_REPO_URL        ( = repo.url       setting )
-- CGIT_REPO_NAME       ( = repo.name      setting )
-- CGIT_REPO_PATH       ( = repo.path      setting )
-- CGIT_REPO_OWNER      ( = repo.owner     setting )
-- CGIT_REPO_DEFBRANCH  ( = repo.defbranch setting )
-- CGIT_REPO_SECTION    ( = section        setting )
-- CGIT_REPO_CLONE_URL  ( = repo.clone-url setting )
+
+- CGIT_REPO_URL (from repo.url)
+- CGIT_REPO_NAME (from repo.name)
+- CGIT_REPO_PATH (from repo.path)
+- CGIT_REPO_OWNER (from repo.owner)
+- CGIT_REPO_DEFBRANCH (from repo.defbranch)
+- CGIT_REPO_SECTION (from repo.section)
+- CGIT_REPO_CLONE_URL (from repo.clone-url)
 
 If a setting is not defined for a repository and the corresponding global
 setting is also not defined (if applicable), then the corresponding
 environment variable will be an empty string.
 
-Note that under normal circumstance all these environment variables are
-defined. If however the total size of the defined settings exceed the
-allocated buffer within cgit then only the environment variables that fit
-in the allocated buffer are handed to the filter.
-
 
 MACRO EXPANSION
 ---------------