Fix a number of minor typos

PROGRESS

@@ -29,31 +29,31 @@ Exercises [ ] gnarly macro required
 Copy      [X]
 Exercises [X]
 
-* Exericse 5: Lifetimes on Types
+* Exercise 5: Lifetimes on Types
 
 Copy      [X]
 Exercises [X] (confirm I like the exercise here)
 
-* Exericse 6: Lifetimes on Impls
+* Exercise 6: Lifetimes on Impls
 
 Copy      [X]
 Exercises [X] (confirm I like the exercise here)
 
-* Exericse 7: Special Lifetimes
+* Exercise 7: Special Lifetimes
 
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 exercises [X]
 
-* Exericse 8: Finale
+* Exercise 8: Finale
 
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 exercises [X]
 
-* Exericse 9: Further Reading
+* Exercise 9: Further Reading
 
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-* Exericse 10: Footnote
+* Exercise 10: Footnote
 
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exercises/01_lifetimes_needed/README.md

@@ -110,7 +110,7 @@ It's possible that in simple cases it could. But your compiler might decide that
 lifetimes. Or it could succeed in inferring them... after 6 months.
 
 So, the compiler needs more information. That information is provided by lifetime annotations.
-Before we discuss them in detail, here is an exercise that will hopefully re-inforce the concepts,
+Before we discuss them in detail, here is an exercise that will hopefully re-enforce the concepts,
 before we deal with syntax.
 
 ## Exercise: Identify which programs work, and which break

exercises/04_mutable_references_and_containers/README.md

@@ -107,7 +107,7 @@ This seems strange -- why can't you borrow `my_vec`?
 
 Well, let's walk through what the compiler sees:
 
-`&val` needs to last for as long as `my_vec` exists:
+`&val1` needs to last for as long as `my_vec` exists:
 
 ``` rust,ignore
 # fn insert_value<'one_lifetime>(my_vec: &'one_lifetime mut Vec<&'one_lifetime i32>, value: &'one_lifetime i32) {

exercises/07_special_lifetimes/README.md

@@ -157,7 +157,7 @@ To quote the Rust Reference:
 You have been given code which contains many uses of the lifetimes `'a` and `'b'`.
 All of these lifetimes can be replaced with either `'_` or `'static`.
 
-Your task is to replace every occurance of the lifetimes `'a` and `'b` with either
+Your task is to replace every occurrence of the lifetimes `'a` and `'b` with either
 `'_` or `'static`, to remove excessive lifetime declarations, and to ensure your 
 code still compiles.