ctags: add page (#3852)

pages/common/ctags.md

@@ -0,0 +1,16 @@
+# ctags
+
+> Generates an index (or tag) file of language objects found in source files for many popular programming languages.
+> More information: <https://ctags.io/>.
+
+- Generate tags for a single file, and output them to a file named "tags" in the current directory, overwriting the file if it exists:
+
+`ctags {{path/to/file}}`
+
+- Generate tags for all files in the current directory, and output them to a specific file, overwriting the file if it exists:
+
+`ctags -f {{filename}} *`
+
+- Generate tags for all files in the current directory and all subdirectories:
+
+`ctags --recurse`