Add documentation for new configuration possibilities

[jonaslagoni]

package.json .{NAME}rc .{NAME}rc.json .{NAME}rc.yaml .{NAME}rc.yml .{NAME}rc.js .{NAME}rc.ts .{NAME}rc.cjs .config/{NAME}rc .config/{NAME}rc.json .config/{NAME}rc.yaml .config/{NAME}rc.yml .config/{NAME}rc.js .config/{NAME}rc.ts .config/{NAME}rc.mjs .config/{NAME}rc.cjs {NAME}.config.js {NAME}.config.ts {NAME}.config.mjs {NAME}.config.cjs {NAME}.json {NAME}.yaml {NAME}.yml {NAME}.js {NAME}.ts {NAME}.mjs {NAME}.cjs