Fix a typo and use rustc instead of Rustc (#419)

Co-authored-by: simonsan <[email protected]>

src/anti_patterns/deny-warnings.md

@@ -54,7 +54,7 @@ Travis, but remember that this may break the build when something changes)
 without requiring a change to the code.
 
 Alternatively, we can specify the lints that we want to `deny` in the code. Here
-is a list of warning lints that is (hopefully) safe to deny (as of Rustc
+is a list of warning lints that is (hopefully) safe to deny (as of rustc
 1.48.0):
 
 ```rust,ignore

src/patterns/ffi/wrappers.md

@@ -114,7 +114,7 @@ pub mod unsafe_module {
     // other module content
 
     pub fn myset_store(myset: *mut MySetWrapper, key: datum, value: datum) -> libc::c_int {
-        // DO NOT USE THIS CODE. IT IS UNSAFE TO DEMONSTRATE A PROLBEM.
+        // DO NOT USE THIS CODE. IT IS UNSAFE TO DEMONSTRATE A PROBLEM.
 
         let myset: &mut MySet = unsafe {
             // SAFETY: whoops, UB occurs in here!