dconf*: add/refresh pages (#8031)

* Fix top description:
- simplify description
- change `See also` link to `gsettings`
- fix man page url to manned.org because an old one is inaccessible

* Provide more examples and enhance existing ones:
- in `dconf`

* Add `dconf-read` page

* More `See also` links in `dconf`

* Add `reset` example

* Add `dconf-reset` page

* Refresh `dconf-write`:
- add link to `dconf` in `See also`
- fix man page url
- standardize examples with other `dconf` pages

* Fix man page urls everywhere in `dconf` pages

pages/linux/dconf-read.md

@@ -0,0 +1,13 @@
+# dconf read
+
+> Read key values from dconf databases.
+> See also: `dconf`.
+> More information: <https://manned.org/dconf>.
+
+- Print a specific key value:
+
+`dconf read {{/path/to/key}}`
+
+- Print a specific key [d]efault value:
+
+`dconf read -d {{/path/to/key}}`