[otbn] Remove non-ASCII character from spec
Signed-off-by: Philipp Wagner <phw@lowrisc.org>
diff --git a/hw/ip/otbn/doc/_index.md b/hw/ip/otbn/doc/_index.md
index 0e0496a..a0460f6 100644
--- a/hw/ip/otbn/doc/_index.md
+++ b/hw/ip/otbn/doc/_index.md
@@ -46,7 +46,7 @@
* The **base instruction subset** operates on the 32b General Purpose Registers (GPRs).
Its instructions are used for the control flow of a OTBN application.
- The base instructions are inspired by RISC-V’s RV32I instruction set, but not compatible with it.
+ The base instructions are inspired by RISC-V's RV32I instruction set, but not compatible with it.
* The **big number instruction subset** operates on 256b Wide Data Registers (WDRs).
Its instructions are used for data processing.
