Rename data directories

The new names are a little clearer.
Add README for Sanskrit Heritage Site data
Add learnsanskrit.org/inflected-pronouns.csv
Add learnsanskrit.org/compounded-pronouns.csv

Pronoun bases are named according to the Paninian convention.
Add learnsanskrit.org/nouns-irregular-complete.csv

There are many more to add, but this is good enough for now.
Fix references in README
Rename pronoun CSV files

It's easier if the part of speech comes first.
Fix typo in sanskrit-heritage-site README
Expand learnsanskrit.org/README
Clean up sanskrit-heritage-site/README and headers

Specifically:
- alphabetize column types
- rename `name` to `form` for clarity/consistency
- add more line breaks
Add .../adjectives-irregular-complete.csv
Add learnsanskrit.org/nominal-endings.csv
Add .../nominal-endings-compounded.csv
Add description for learnsanskrit.org data
Rename inflected noun/adjective data
Expand scrape_utils.py
Fix miscellaneous whitespace
Change word in README
Add note about stem genders
Remove comma