chore: fix some typos in comments

Signed-off-by: tgolang <seekseat@aliyun.com>

risc0/circuit/rv32im/src/prove/emu/preflight/mod.rs

@@ -280,7 +280,7 @@ impl Preflight {
     fn post_steps(&mut self) -> Result<()> {
         let faults = self.pager.get_faults();
 
-        // Emulate the page fault reads occuring before the body starts.
+        // Emulate the page fault reads occurring before the body starts.
         for page_idx in faults.reads.iter().rev() {
             self.page_fault(true, /*is_read=*/ 1, *page_idx, /*is_done=*/ 0)?;
         }

risc0/circuit/rv32im/src/prove/emu/rv32im.rs

@@ -286,7 +286,7 @@ const RV32IM_ISA: InstructionTable = [
 // - Opcode: 7 bits
 // - Func3: 3 bits
 // - Func7: 7 bits
-// In many cases, func7 and/or func3 is ignored.  A stardard trick is to decode
+// In many cases, func7 and/or func3 is ignored.  A standard trick is to decode
 // via a table, but a 17 bit lookup table destroys L1 cache.  Luckily for us,
 // in practice the low 2 bits of opcode are always 11, so we can drop them, and
 // also func7 is always either 0, 1, 0x20 or don't care, so we can reduce func7

risc0/core/src/field/mod.rs

@@ -298,7 +298,7 @@ mod tests {
     where
         F: Into<u64> + From<u64> + Debug,
     {
-        // For testng, we do 128-bit arithmetic so we don't have to worry about
+        // For testing, we do 128-bit arithmetic so we don't have to worry about
         // overflows.
         let p: u128 = p_u64 as _;