Fix misspelling and shorten sentences in manual

docs/manual/embedded-programming.qmd

@@ -5,10 +5,8 @@ embedded environment\index{embedded systems}.
 
 ## Performance {-}
 
-*TinyExpr++* is fairly fast compared to compiled C when the expression is short, when the
-expression does hard calculations (e.g., exponentiation), and when some of the
-work can be simplified by `evaluate()`. *TinyExpr++* is slower compared to C when the
-expression is long and involves only basic arithmetic.
+*TinyExpr++* is fairly fast compared to compiled C when the expression is short or does hard calculations (e.g., exponentiation).
+*TinyExpr++* is slower compared to C when the expression is long and involves only basic arithmetic.
 
 Here are some example benchmarks:
 

docs/manual/operators.qmd

@@ -52,7 +52,7 @@ $$
 You can override it so that the additions happen first (resulting in `15`), followed by the division (finally yielding `7.5`).
 Likewise, `(2+5)^2` will yield `49` (`7` squared), while `2+5^2` will yield `27` (`5` squared, plus `2`).
 
-## Compatability Note {-}
+## Compatibility Note {-}
 
 The `%` character acts as a modulus operator in *TinyExpr++*, which is different from most
 spreadsheet programs. In programs such as *LibreOffice Calc* and *Excel*, `%` is used

docs/manual/unknown-symbol-resolution.qmd

@@ -1,6 +1,6 @@
 # Handling Unknown Variables {#sec-usr}
 
-Although it is possible to add [custom variables](#custom-variables) to the parser, there may be times when you can't
+Although it is possible to add [variables](#custom-variables) to the parser, there may be times when you can't
 anticipate the exact variable\index{variables!unknown|see{unknown symbols}} names that a user will enter. For example, a user could enter
 variables representing fiscal years in the format of `FY[year]`. From there, they would like to perform operation
 such as getting the range between them. In this situation, their expression may be something like this: