Please do not just jump right into indexing without careful consideration.
Read and understand the In & Out > Importing & Indexing section of the Help or manual before committing to indexing. Pay special attention to the Indexing and the file system subsection.
Thank you for the kind admonition, Jim! I used to index all my Markdown files when I was using Obsidian, but slater switched to import only and write in DT instead.