docs: Adding periphery rules.

Updates and documentation originally improved and then release by
Kevin Kelly <kevin.kelley@skywatertechnology.com> to Google for imported
into the docutils RST format by Tim 'mithro' Ansell <tansell@google.com>.

Signed-off-by: Kevin Kelley <kevin.kelley@skywatertechnology.com>
Signed-off-by: Tim 'mithro' Ansell <tansell@google.com>
diff --git a/docs/rules/periphery/p031-photo_dotdash.csv b/docs/rules/periphery/p031-photo_dotdash.csv
new file mode 100644
index 0000000..cfa8467
--- /dev/null
+++ b/docs/rules/periphery/p031-photo_dotdash.csv
@@ -0,0 +1,11 @@
+Name,Description,Flags,Value

+(photo.1),Rules dnwell.3 and nwell.5 are exempted for photoDiode,,

+(photo.2),Min/Max width of photoDiode,,3.000

+(photo.3),Min spacing between photoDiode,,5.000

+(photo.4),Min spacing between photoDiode and deep nwell,,5.300

+(photo.5),photoDiode edges must be coincident with :drc_tag:`areaid.po`,,

+(photo.6),photoDiode must be enclosed by dnwell ring,,

+(photo.7),photoDiode must be enclosed by p+ tap ring,,

+(photo.8),Min/Max width of nwell inside photoDiode,,0.840

+(photo.9),Min/Max enclosure of nwell by photoDiode,,1.080

+(photo.10),Min/Max width of tap inside photoDiode,,0.410