curl.1: provide examples for each option

The file format for each option now features a "Example:" header that
can provide one or more examples that get rendered appropriately in the
output. All options MUST have at least one example or gen.pl complains
at build-time.

This fix also does a few other minor format and consistency cleanups.

Closes #7654

docs/cmdline-opts/trace-ascii.d

diff --git a/docs/cmdline-opts/trace-ascii.d b/docs/cmdline-opts/trace-ascii.d
index 461ea6f..89fe588 100644
--- a/docs/cmdline-opts/trace-ascii.d
+++ b/docs/cmdline-opts/trace-ascii.d
@@ -3,6 +3,7 @@
 Help: Like --trace, but without hex output
 Mutexed: trace verbose
 Category: verbose
+Example: --trace-ascii log.txt $URL
 ---
 Enables a full trace dump of all incoming and outgoing data, including
 descriptive information, to the given output file. Use "-" as filename to have