Apply suggestions from code review

Co-authored-by: Emilio López <2642849+elopez@users.noreply.github.com>

Author: gustavo-grieco

program-analysis/echidna/configuration.md

@@ -411,7 +411,7 @@ The SMT solver used when doing symbolic execution. Valid values are: "cvc5", "z3
 
 | Type | Default | Available in |
 | ---- | ------- | ------------ |
-| Int | `10` | 2.2.4+ |
+| Int | `10` | 2.2.8+ |
 
 Number of states in base 2 (e.g. `2 ** 10`) that we may explore using symbolic execution. Only relevant if
 `symExec` is true.
@@ -507,8 +507,7 @@ part of the corpus on the `gas_info` field. This functionality was experimental.
 
 | Type | Default | Available in |
 | ---- | ------- | -------------- |
-| Bool | `true` | \* until 2.2.8 |
+| Bool | `true` | \* until 2.2.7 |
 
-Whether symbolic execution will be concolic (vs full symbolic execution). Only
-relevant if `symExec` is true.
+This option controlled whether symbolic execution will be concolic (vs full symbolic execution). It has been removed from the current version of Echidna.