doc: fix typos in Formula Cookbook

`preprended` > `prepended`
Replace `a` with `an`
`throughly` > `thoroughly`
Remove extra `consider`

Closes Homebrew/homebrew#48697.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

share/doc/homebrew/Formula-Cookbook.md

@@ -74,7 +74,7 @@ so you can override this with `brew create <url> --set-name <name>`.
 
 A SSL/TLS (https) [`homepage`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#homepage%3D-class_method) is preferred, if one is available.
 
-Try to summarize from the [`homepage`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#homepage%3D-class_method) what the formula does in the [`desc`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#desc%3D-class_method)ription. Note that the [`desc`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#desc%3D-class_method)ription is automatically preprended with the formula name.
+Try to summarize from the [`homepage`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#homepage%3D-class_method) what the formula does in the [`desc`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#desc%3D-class_method)ription. Note that the [`desc`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#desc%3D-class_method)ription is automatically prepended with the formula name.
 
 ## Check the build system
 
@@ -165,7 +165,7 @@ Sometimes there’s hard conflict between formulae, and it can’t be avoided or
 `mbedtls` ships and compiles a "Hello World" executable. This is obviously non-essential to `mbedtls`’s functionality, and conflict with the popular GNU `hello` formula would be overkill, so we just remove it.
 
 [pdftohtml](https://github.com/Homebrew/homebrew/blob/master/Library/Formula/pdftohtml.rb) provides an example of a serious
-conflict, where both formula ship a identically-named binary that is essential to functionality, so a [`conflicts_with`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#conflicts_with-class_method) is preferable.
+conflict, where both formula ship an identically-named binary that is essential to functionality, so a [`conflicts_with`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#conflicts_with-class_method) is preferable.
 
 As a general rule, [`conflicts_with`](http://www.rubydoc.info/github/Homebrew/homebrew/master/Formula#conflicts_with-class_method) should be a last-resort option. It’s a fairly blunt instrument.
 
@@ -303,7 +303,7 @@ The established standard for Git commit messages is:
 
 * the first line is a commit summary of *50 characters or less*
 * two (2) newlines, then
-* explain the commit throughly
+* explain the commit thoroughly
 
 At Homebrew, we like to put the name of the formula up front like so: `foobar 7.3 (new formula)`.
 This may seem crazy short, but you’ll find that forcing yourself to summarise the commit encourages you to be atomic and concise. If you can’t summarise it in 50-80 characters, you’re probably trying to commit two commits as one. For a more thorough explanation, please read Tim Pope’s excellent blog post, [A Note About Git Commit Messages](http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html).
@@ -815,7 +815,7 @@ When using Homebrew's `gfortran` compiler, the standard `CFLAGS` are used and us
 
 # How to start over (reset to  upstream `master`)
 
-Have you created a real mess in git which stops you from creating a commit you want to submit to us? You might want to consider consider starting again from scratch. Your changes can be reset to the Homebrew's `master` branch by running:
+Have you created a real mess in git which stops you from creating a commit you want to submit to us? You might want to consider starting again from scratch. Your changes can be reset to the Homebrew's `master` branch by running:
 
 ```shell
 git checkout -f master