general: Reformat documentation with better formatting and wording

General purpose reformating and rewording in (a few places). This should
also make markdown linting happier.

Prefer back-ticks wherever useful and use `console` for code blocks to
be executed on terminal.

Also, update references links wherever possible (including update from
'http://' to 'https://').

modules/dnf/README.md

@@ -1,29 +1,25 @@
-DNF
-===
+# DNF
 
 Defines [dnf][1] aliases.
 
-Aliases
--------
+## Aliases
 
-  - `dnfc` removes package(s) and leaves.
-  - `dnfi` installs package(s).
-  - `dnfh` displays history.
-  - `dnfl` lists packages.
-  - `dnfL` lists installed packages.
-  - `dnfq` displays package information.
-  - `dnfr` removes package(s).
-  - `dnfs` searches for a package.
-  - `dnfu` updates packages.
-  - `dnfU` upgrades packages.
+- `dnfc` removes package(s) and leaves.
+- `dnfi` installs package(s).
+- `dnfh` displays history.
+- `dnfl` lists packages.
+- `dnfL` lists installed packages.
+- `dnfq` displays package information.
+- `dnfr` removes package(s).
+- `dnfs` searches for a package.
+- `dnfu` updates packages.
+- `dnfU` upgrades packages.
 
-Authors
--------
+## Authors
 
 *The authors of this module should be contacted via the [issue tracker][2].*
 
-  - [Sorin Ionescu](https://github.com/sorin-ionescu)
+- [Sorin Ionescu](https://github.com/sorin-ionescu)
 
 [1]: https://fedoraproject.org/wiki/Features/DNF
 [2]: https://github.com/sorin-ionescu/prezto/issues
-