recsel: add page (#4309)

pages/common/recsel.md

@@ -0,0 +1,16 @@
+# recsel
+
+> Print records from a recfile: a human-editable, plain text database.
+> More information: <https://www.gnu.org/software/recutils/manual/recutils.html>.
+
+- Extract name and version field:
+
+`recsel -p name,version {{data.rec}}`
+
+- Use "~" to match a string with a given regular expression:
+
+`recsel -e "{{field_name}}  ~ '{{pattern_regex}}' {{data.rec}}"`
+
+- Use a predicate to match a name and a version:
+
+`recsel -e "name ~ '{{pattern_regex}}' && version ~ '{{pattern_regex}}'" {{data.rec}}`